mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-06 02:56:44 +07:00
6923715ae3
I noticed a blank line in blktrace output. This patch fixes that. Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2672 lines
64 KiB
C
2672 lines
64 KiB
C
/*
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* CFQ, or complete fairness queueing, disk scheduler.
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*
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* Based on ideas from a previously unfinished io
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* scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
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*
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* Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
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*/
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#include <linux/module.h>
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#include <linux/blkdev.h>
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#include <linux/elevator.h>
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#include <linux/rbtree.h>
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#include <linux/ioprio.h>
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#include <linux/blktrace_api.h>
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/*
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* tunables
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*/
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/* max queue in one round of service */
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static const int cfq_quantum = 4;
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static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
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/* maximum backwards seek, in KiB */
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static const int cfq_back_max = 16 * 1024;
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/* penalty of a backwards seek */
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static const int cfq_back_penalty = 2;
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static const int cfq_slice_sync = HZ / 10;
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static int cfq_slice_async = HZ / 25;
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static const int cfq_slice_async_rq = 2;
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static int cfq_slice_idle = HZ / 125;
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/*
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* offset from end of service tree
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*/
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#define CFQ_IDLE_DELAY (HZ / 5)
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/*
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* below this threshold, we consider thinktime immediate
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*/
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#define CFQ_MIN_TT (2)
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#define CFQ_SLICE_SCALE (5)
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#define CFQ_HW_QUEUE_MIN (5)
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#define RQ_CIC(rq) \
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((struct cfq_io_context *) (rq)->elevator_private)
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#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2)
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static struct kmem_cache *cfq_pool;
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static struct kmem_cache *cfq_ioc_pool;
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static DEFINE_PER_CPU(unsigned long, ioc_count);
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static struct completion *ioc_gone;
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static DEFINE_SPINLOCK(ioc_gone_lock);
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#define CFQ_PRIO_LISTS IOPRIO_BE_NR
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#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
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#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
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#define sample_valid(samples) ((samples) > 80)
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/*
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* Most of our rbtree usage is for sorting with min extraction, so
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* if we cache the leftmost node we don't have to walk down the tree
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* to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
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* move this into the elevator for the rq sorting as well.
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*/
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struct cfq_rb_root {
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struct rb_root rb;
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struct rb_node *left;
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};
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#define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, }
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/*
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* Per block device queue structure
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*/
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struct cfq_data {
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struct request_queue *queue;
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/*
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* rr list of queues with requests and the count of them
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*/
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struct cfq_rb_root service_tree;
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/*
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* Each priority tree is sorted by next_request position. These
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* trees are used when determining if two or more queues are
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* interleaving requests (see cfq_close_cooperator).
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*/
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struct rb_root prio_trees[CFQ_PRIO_LISTS];
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unsigned int busy_queues;
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/*
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* Used to track any pending rt requests so we can pre-empt current
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* non-RT cfqq in service when this value is non-zero.
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*/
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unsigned int busy_rt_queues;
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int rq_in_driver;
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int sync_flight;
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/*
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* queue-depth detection
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*/
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int rq_queued;
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int hw_tag;
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int hw_tag_samples;
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int rq_in_driver_peak;
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/*
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* idle window management
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*/
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struct timer_list idle_slice_timer;
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struct work_struct unplug_work;
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struct cfq_queue *active_queue;
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struct cfq_io_context *active_cic;
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/*
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* async queue for each priority case
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*/
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struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
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struct cfq_queue *async_idle_cfqq;
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sector_t last_position;
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/*
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* tunables, see top of file
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*/
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unsigned int cfq_quantum;
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unsigned int cfq_fifo_expire[2];
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unsigned int cfq_back_penalty;
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unsigned int cfq_back_max;
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unsigned int cfq_slice[2];
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unsigned int cfq_slice_async_rq;
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unsigned int cfq_slice_idle;
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struct list_head cic_list;
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};
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/*
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* Per process-grouping structure
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*/
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struct cfq_queue {
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/* reference count */
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atomic_t ref;
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/* various state flags, see below */
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unsigned int flags;
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/* parent cfq_data */
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struct cfq_data *cfqd;
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/* service_tree member */
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struct rb_node rb_node;
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/* service_tree key */
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unsigned long rb_key;
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/* prio tree member */
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struct rb_node p_node;
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/* prio tree root we belong to, if any */
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struct rb_root *p_root;
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/* sorted list of pending requests */
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struct rb_root sort_list;
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/* if fifo isn't expired, next request to serve */
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struct request *next_rq;
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/* requests queued in sort_list */
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int queued[2];
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/* currently allocated requests */
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int allocated[2];
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/* fifo list of requests in sort_list */
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struct list_head fifo;
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unsigned long slice_end;
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long slice_resid;
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unsigned int slice_dispatch;
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/* pending metadata requests */
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int meta_pending;
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/* number of requests that are on the dispatch list or inside driver */
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int dispatched;
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/* io prio of this group */
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unsigned short ioprio, org_ioprio;
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unsigned short ioprio_class, org_ioprio_class;
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pid_t pid;
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};
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enum cfqq_state_flags {
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CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
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CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
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CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
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CFQ_CFQQ_FLAG_must_alloc, /* must be allowed rq alloc */
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CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
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CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
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CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
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CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
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CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
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CFQ_CFQQ_FLAG_sync, /* synchronous queue */
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CFQ_CFQQ_FLAG_coop, /* has done a coop jump of the queue */
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};
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#define CFQ_CFQQ_FNS(name) \
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static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
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{ \
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(cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
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} \
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static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
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{ \
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(cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
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} \
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static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
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{ \
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return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
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}
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CFQ_CFQQ_FNS(on_rr);
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CFQ_CFQQ_FNS(wait_request);
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CFQ_CFQQ_FNS(must_dispatch);
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CFQ_CFQQ_FNS(must_alloc);
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CFQ_CFQQ_FNS(must_alloc_slice);
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CFQ_CFQQ_FNS(fifo_expire);
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CFQ_CFQQ_FNS(idle_window);
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CFQ_CFQQ_FNS(prio_changed);
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CFQ_CFQQ_FNS(slice_new);
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CFQ_CFQQ_FNS(sync);
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CFQ_CFQQ_FNS(coop);
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#undef CFQ_CFQQ_FNS
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#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
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blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
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#define cfq_log(cfqd, fmt, args...) \
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blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
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static void cfq_dispatch_insert(struct request_queue *, struct request *);
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static struct cfq_queue *cfq_get_queue(struct cfq_data *, int,
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struct io_context *, gfp_t);
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static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
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struct io_context *);
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static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
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int is_sync)
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{
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return cic->cfqq[!!is_sync];
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}
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static inline void cic_set_cfqq(struct cfq_io_context *cic,
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struct cfq_queue *cfqq, int is_sync)
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{
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cic->cfqq[!!is_sync] = cfqq;
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}
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/*
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* We regard a request as SYNC, if it's either a read or has the SYNC bit
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* set (in which case it could also be direct WRITE).
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*/
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static inline int cfq_bio_sync(struct bio *bio)
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{
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if (bio_data_dir(bio) == READ || bio_sync(bio))
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return 1;
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return 0;
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}
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/*
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* scheduler run of queue, if there are requests pending and no one in the
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* driver that will restart queueing
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*/
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static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
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{
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if (cfqd->busy_queues) {
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cfq_log(cfqd, "schedule dispatch");
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kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
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}
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}
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static int cfq_queue_empty(struct request_queue *q)
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{
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struct cfq_data *cfqd = q->elevator->elevator_data;
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return !cfqd->busy_queues;
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}
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/*
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* Scale schedule slice based on io priority. Use the sync time slice only
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* if a queue is marked sync and has sync io queued. A sync queue with async
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* io only, should not get full sync slice length.
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*/
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static inline int cfq_prio_slice(struct cfq_data *cfqd, int sync,
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unsigned short prio)
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{
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const int base_slice = cfqd->cfq_slice[sync];
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WARN_ON(prio >= IOPRIO_BE_NR);
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return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
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}
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static inline int
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cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
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{
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return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
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}
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static inline void
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cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
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{
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cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies;
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cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
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}
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/*
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* We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
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* isn't valid until the first request from the dispatch is activated
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* and the slice time set.
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*/
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static inline int cfq_slice_used(struct cfq_queue *cfqq)
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{
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if (cfq_cfqq_slice_new(cfqq))
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return 0;
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if (time_before(jiffies, cfqq->slice_end))
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return 0;
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return 1;
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}
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/*
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* Lifted from AS - choose which of rq1 and rq2 that is best served now.
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* We choose the request that is closest to the head right now. Distance
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* behind the head is penalized and only allowed to a certain extent.
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*/
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static struct request *
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cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2)
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{
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sector_t last, s1, s2, d1 = 0, d2 = 0;
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unsigned long back_max;
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#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
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#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
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unsigned wrap = 0; /* bit mask: requests behind the disk head? */
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if (rq1 == NULL || rq1 == rq2)
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return rq2;
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if (rq2 == NULL)
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return rq1;
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if (rq_is_sync(rq1) && !rq_is_sync(rq2))
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return rq1;
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else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
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return rq2;
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if (rq_is_meta(rq1) && !rq_is_meta(rq2))
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return rq1;
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else if (rq_is_meta(rq2) && !rq_is_meta(rq1))
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return rq2;
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s1 = blk_rq_pos(rq1);
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s2 = blk_rq_pos(rq2);
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last = cfqd->last_position;
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/*
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* by definition, 1KiB is 2 sectors
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*/
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back_max = cfqd->cfq_back_max * 2;
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/*
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* Strict one way elevator _except_ in the case where we allow
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* short backward seeks which are biased as twice the cost of a
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* similar forward seek.
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*/
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if (s1 >= last)
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d1 = s1 - last;
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else if (s1 + back_max >= last)
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d1 = (last - s1) * cfqd->cfq_back_penalty;
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else
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wrap |= CFQ_RQ1_WRAP;
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if (s2 >= last)
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d2 = s2 - last;
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else if (s2 + back_max >= last)
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d2 = (last - s2) * cfqd->cfq_back_penalty;
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else
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wrap |= CFQ_RQ2_WRAP;
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/* Found required data */
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/*
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* By doing switch() on the bit mask "wrap" we avoid having to
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* check two variables for all permutations: --> faster!
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*/
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switch (wrap) {
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case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
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if (d1 < d2)
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return rq1;
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else if (d2 < d1)
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return rq2;
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else {
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if (s1 >= s2)
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return rq1;
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else
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return rq2;
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}
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case CFQ_RQ2_WRAP:
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return rq1;
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case CFQ_RQ1_WRAP:
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return rq2;
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case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
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default:
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/*
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* Since both rqs are wrapped,
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* start with the one that's further behind head
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* (--> only *one* back seek required),
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* since back seek takes more time than forward.
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*/
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if (s1 <= s2)
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return rq1;
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else
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return rq2;
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}
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}
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/*
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* The below is leftmost cache rbtree addon
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*/
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static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
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{
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if (!root->left)
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root->left = rb_first(&root->rb);
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if (root->left)
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return rb_entry(root->left, struct cfq_queue, rb_node);
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return NULL;
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}
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static void rb_erase_init(struct rb_node *n, struct rb_root *root)
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{
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rb_erase(n, root);
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RB_CLEAR_NODE(n);
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}
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static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
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{
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if (root->left == n)
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root->left = NULL;
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rb_erase_init(n, &root->rb);
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}
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/*
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* would be nice to take fifo expire time into account as well
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*/
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static struct request *
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cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
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struct request *last)
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{
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struct rb_node *rbnext = rb_next(&last->rb_node);
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struct rb_node *rbprev = rb_prev(&last->rb_node);
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struct request *next = NULL, *prev = NULL;
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BUG_ON(RB_EMPTY_NODE(&last->rb_node));
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if (rbprev)
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prev = rb_entry_rq(rbprev);
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if (rbnext)
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next = rb_entry_rq(rbnext);
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else {
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rbnext = rb_first(&cfqq->sort_list);
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if (rbnext && rbnext != &last->rb_node)
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next = rb_entry_rq(rbnext);
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}
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return cfq_choose_req(cfqd, next, prev);
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}
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static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
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struct cfq_queue *cfqq)
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{
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/*
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* just an approximation, should be ok.
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*/
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return (cfqd->busy_queues - 1) * (cfq_prio_slice(cfqd, 1, 0) -
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cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
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}
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/*
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* The cfqd->service_tree holds all pending cfq_queue's that have
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* requests waiting to be processed. It is sorted in the order that
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* we will service the queues.
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*/
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static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
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int add_front)
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{
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struct rb_node **p, *parent;
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struct cfq_queue *__cfqq;
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unsigned long rb_key;
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int left;
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if (cfq_class_idle(cfqq)) {
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rb_key = CFQ_IDLE_DELAY;
|
|
parent = rb_last(&cfqd->service_tree.rb);
|
|
if (parent && parent != &cfqq->rb_node) {
|
|
__cfqq = rb_entry(parent, struct cfq_queue, rb_node);
|
|
rb_key += __cfqq->rb_key;
|
|
} else
|
|
rb_key += jiffies;
|
|
} else if (!add_front) {
|
|
rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
|
|
rb_key += cfqq->slice_resid;
|
|
cfqq->slice_resid = 0;
|
|
} else
|
|
rb_key = 0;
|
|
|
|
if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
|
|
/*
|
|
* same position, nothing more to do
|
|
*/
|
|
if (rb_key == cfqq->rb_key)
|
|
return;
|
|
|
|
cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
|
|
}
|
|
|
|
left = 1;
|
|
parent = NULL;
|
|
p = &cfqd->service_tree.rb.rb_node;
|
|
while (*p) {
|
|
struct rb_node **n;
|
|
|
|
parent = *p;
|
|
__cfqq = rb_entry(parent, struct cfq_queue, rb_node);
|
|
|
|
/*
|
|
* sort RT queues first, we always want to give
|
|
* preference to them. IDLE queues goes to the back.
|
|
* after that, sort on the next service time.
|
|
*/
|
|
if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq))
|
|
n = &(*p)->rb_left;
|
|
else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq))
|
|
n = &(*p)->rb_right;
|
|
else if (cfq_class_idle(cfqq) < cfq_class_idle(__cfqq))
|
|
n = &(*p)->rb_left;
|
|
else if (cfq_class_idle(cfqq) > cfq_class_idle(__cfqq))
|
|
n = &(*p)->rb_right;
|
|
else if (rb_key < __cfqq->rb_key)
|
|
n = &(*p)->rb_left;
|
|
else
|
|
n = &(*p)->rb_right;
|
|
|
|
if (n == &(*p)->rb_right)
|
|
left = 0;
|
|
|
|
p = n;
|
|
}
|
|
|
|
if (left)
|
|
cfqd->service_tree.left = &cfqq->rb_node;
|
|
|
|
cfqq->rb_key = rb_key;
|
|
rb_link_node(&cfqq->rb_node, parent, p);
|
|
rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb);
|
|
}
|
|
|
|
static struct cfq_queue *
|
|
cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
|
|
sector_t sector, struct rb_node **ret_parent,
|
|
struct rb_node ***rb_link)
|
|
{
|
|
struct rb_node **p, *parent;
|
|
struct cfq_queue *cfqq = NULL;
|
|
|
|
parent = NULL;
|
|
p = &root->rb_node;
|
|
while (*p) {
|
|
struct rb_node **n;
|
|
|
|
parent = *p;
|
|
cfqq = rb_entry(parent, struct cfq_queue, p_node);
|
|
|
|
/*
|
|
* Sort strictly based on sector. Smallest to the left,
|
|
* largest to the right.
|
|
*/
|
|
if (sector > blk_rq_pos(cfqq->next_rq))
|
|
n = &(*p)->rb_right;
|
|
else if (sector < blk_rq_pos(cfqq->next_rq))
|
|
n = &(*p)->rb_left;
|
|
else
|
|
break;
|
|
p = n;
|
|
cfqq = NULL;
|
|
}
|
|
|
|
*ret_parent = parent;
|
|
if (rb_link)
|
|
*rb_link = p;
|
|
return cfqq;
|
|
}
|
|
|
|
static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
struct rb_node **p, *parent;
|
|
struct cfq_queue *__cfqq;
|
|
|
|
if (cfqq->p_root) {
|
|
rb_erase(&cfqq->p_node, cfqq->p_root);
|
|
cfqq->p_root = NULL;
|
|
}
|
|
|
|
if (cfq_class_idle(cfqq))
|
|
return;
|
|
if (!cfqq->next_rq)
|
|
return;
|
|
|
|
cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
|
|
__cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
|
|
blk_rq_pos(cfqq->next_rq), &parent, &p);
|
|
if (!__cfqq) {
|
|
rb_link_node(&cfqq->p_node, parent, p);
|
|
rb_insert_color(&cfqq->p_node, cfqq->p_root);
|
|
} else
|
|
cfqq->p_root = NULL;
|
|
}
|
|
|
|
/*
|
|
* Update cfqq's position in the service tree.
|
|
*/
|
|
static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
/*
|
|
* Resorting requires the cfqq to be on the RR list already.
|
|
*/
|
|
if (cfq_cfqq_on_rr(cfqq)) {
|
|
cfq_service_tree_add(cfqd, cfqq, 0);
|
|
cfq_prio_tree_add(cfqd, cfqq);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* add to busy list of queues for service, trying to be fair in ordering
|
|
* the pending list according to last request service
|
|
*/
|
|
static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
|
|
BUG_ON(cfq_cfqq_on_rr(cfqq));
|
|
cfq_mark_cfqq_on_rr(cfqq);
|
|
cfqd->busy_queues++;
|
|
if (cfq_class_rt(cfqq))
|
|
cfqd->busy_rt_queues++;
|
|
|
|
cfq_resort_rr_list(cfqd, cfqq);
|
|
}
|
|
|
|
/*
|
|
* Called when the cfqq no longer has requests pending, remove it from
|
|
* the service tree.
|
|
*/
|
|
static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
|
|
BUG_ON(!cfq_cfqq_on_rr(cfqq));
|
|
cfq_clear_cfqq_on_rr(cfqq);
|
|
|
|
if (!RB_EMPTY_NODE(&cfqq->rb_node))
|
|
cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
|
|
if (cfqq->p_root) {
|
|
rb_erase(&cfqq->p_node, cfqq->p_root);
|
|
cfqq->p_root = NULL;
|
|
}
|
|
|
|
BUG_ON(!cfqd->busy_queues);
|
|
cfqd->busy_queues--;
|
|
if (cfq_class_rt(cfqq))
|
|
cfqd->busy_rt_queues--;
|
|
}
|
|
|
|
/*
|
|
* rb tree support functions
|
|
*/
|
|
static void cfq_del_rq_rb(struct request *rq)
|
|
{
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
struct cfq_data *cfqd = cfqq->cfqd;
|
|
const int sync = rq_is_sync(rq);
|
|
|
|
BUG_ON(!cfqq->queued[sync]);
|
|
cfqq->queued[sync]--;
|
|
|
|
elv_rb_del(&cfqq->sort_list, rq);
|
|
|
|
if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
|
|
cfq_del_cfqq_rr(cfqd, cfqq);
|
|
}
|
|
|
|
static void cfq_add_rq_rb(struct request *rq)
|
|
{
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
struct cfq_data *cfqd = cfqq->cfqd;
|
|
struct request *__alias, *prev;
|
|
|
|
cfqq->queued[rq_is_sync(rq)]++;
|
|
|
|
/*
|
|
* looks a little odd, but the first insert might return an alias.
|
|
* if that happens, put the alias on the dispatch list
|
|
*/
|
|
while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
|
|
cfq_dispatch_insert(cfqd->queue, __alias);
|
|
|
|
if (!cfq_cfqq_on_rr(cfqq))
|
|
cfq_add_cfqq_rr(cfqd, cfqq);
|
|
|
|
/*
|
|
* check if this request is a better next-serve candidate
|
|
*/
|
|
prev = cfqq->next_rq;
|
|
cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq);
|
|
|
|
/*
|
|
* adjust priority tree position, if ->next_rq changes
|
|
*/
|
|
if (prev != cfqq->next_rq)
|
|
cfq_prio_tree_add(cfqd, cfqq);
|
|
|
|
BUG_ON(!cfqq->next_rq);
|
|
}
|
|
|
|
static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
|
|
{
|
|
elv_rb_del(&cfqq->sort_list, rq);
|
|
cfqq->queued[rq_is_sync(rq)]--;
|
|
cfq_add_rq_rb(rq);
|
|
}
|
|
|
|
static struct request *
|
|
cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
struct cfq_io_context *cic;
|
|
struct cfq_queue *cfqq;
|
|
|
|
cic = cfq_cic_lookup(cfqd, tsk->io_context);
|
|
if (!cic)
|
|
return NULL;
|
|
|
|
cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
|
|
if (cfqq) {
|
|
sector_t sector = bio->bi_sector + bio_sectors(bio);
|
|
|
|
return elv_rb_find(&cfqq->sort_list, sector);
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static void cfq_activate_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
|
|
cfqd->rq_in_driver++;
|
|
cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
|
|
cfqd->rq_in_driver);
|
|
|
|
cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
|
|
}
|
|
|
|
static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
|
|
WARN_ON(!cfqd->rq_in_driver);
|
|
cfqd->rq_in_driver--;
|
|
cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
|
|
cfqd->rq_in_driver);
|
|
}
|
|
|
|
static void cfq_remove_request(struct request *rq)
|
|
{
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
|
|
if (cfqq->next_rq == rq)
|
|
cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
|
|
|
|
list_del_init(&rq->queuelist);
|
|
cfq_del_rq_rb(rq);
|
|
|
|
cfqq->cfqd->rq_queued--;
|
|
if (rq_is_meta(rq)) {
|
|
WARN_ON(!cfqq->meta_pending);
|
|
cfqq->meta_pending--;
|
|
}
|
|
}
|
|
|
|
static int cfq_merge(struct request_queue *q, struct request **req,
|
|
struct bio *bio)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct request *__rq;
|
|
|
|
__rq = cfq_find_rq_fmerge(cfqd, bio);
|
|
if (__rq && elv_rq_merge_ok(__rq, bio)) {
|
|
*req = __rq;
|
|
return ELEVATOR_FRONT_MERGE;
|
|
}
|
|
|
|
return ELEVATOR_NO_MERGE;
|
|
}
|
|
|
|
static void cfq_merged_request(struct request_queue *q, struct request *req,
|
|
int type)
|
|
{
|
|
if (type == ELEVATOR_FRONT_MERGE) {
|
|
struct cfq_queue *cfqq = RQ_CFQQ(req);
|
|
|
|
cfq_reposition_rq_rb(cfqq, req);
|
|
}
|
|
}
|
|
|
|
static void
|
|
cfq_merged_requests(struct request_queue *q, struct request *rq,
|
|
struct request *next)
|
|
{
|
|
/*
|
|
* reposition in fifo if next is older than rq
|
|
*/
|
|
if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
|
|
time_before(next->start_time, rq->start_time))
|
|
list_move(&rq->queuelist, &next->queuelist);
|
|
|
|
cfq_remove_request(next);
|
|
}
|
|
|
|
static int cfq_allow_merge(struct request_queue *q, struct request *rq,
|
|
struct bio *bio)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_io_context *cic;
|
|
struct cfq_queue *cfqq;
|
|
|
|
/*
|
|
* Disallow merge of a sync bio into an async request.
|
|
*/
|
|
if (cfq_bio_sync(bio) && !rq_is_sync(rq))
|
|
return 0;
|
|
|
|
/*
|
|
* Lookup the cfqq that this bio will be queued with. Allow
|
|
* merge only if rq is queued there.
|
|
*/
|
|
cic = cfq_cic_lookup(cfqd, current->io_context);
|
|
if (!cic)
|
|
return 0;
|
|
|
|
cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
|
|
if (cfqq == RQ_CFQQ(rq))
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void __cfq_set_active_queue(struct cfq_data *cfqd,
|
|
struct cfq_queue *cfqq)
|
|
{
|
|
if (cfqq) {
|
|
cfq_log_cfqq(cfqd, cfqq, "set_active");
|
|
cfqq->slice_end = 0;
|
|
cfqq->slice_dispatch = 0;
|
|
|
|
cfq_clear_cfqq_wait_request(cfqq);
|
|
cfq_clear_cfqq_must_dispatch(cfqq);
|
|
cfq_clear_cfqq_must_alloc_slice(cfqq);
|
|
cfq_clear_cfqq_fifo_expire(cfqq);
|
|
cfq_mark_cfqq_slice_new(cfqq);
|
|
|
|
del_timer(&cfqd->idle_slice_timer);
|
|
}
|
|
|
|
cfqd->active_queue = cfqq;
|
|
}
|
|
|
|
/*
|
|
* current cfqq expired its slice (or was too idle), select new one
|
|
*/
|
|
static void
|
|
__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
|
|
int timed_out)
|
|
{
|
|
cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
|
|
|
|
if (cfq_cfqq_wait_request(cfqq))
|
|
del_timer(&cfqd->idle_slice_timer);
|
|
|
|
cfq_clear_cfqq_wait_request(cfqq);
|
|
|
|
/*
|
|
* store what was left of this slice, if the queue idled/timed out
|
|
*/
|
|
if (timed_out && !cfq_cfqq_slice_new(cfqq)) {
|
|
cfqq->slice_resid = cfqq->slice_end - jiffies;
|
|
cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
|
|
}
|
|
|
|
cfq_resort_rr_list(cfqd, cfqq);
|
|
|
|
if (cfqq == cfqd->active_queue)
|
|
cfqd->active_queue = NULL;
|
|
|
|
if (cfqd->active_cic) {
|
|
put_io_context(cfqd->active_cic->ioc);
|
|
cfqd->active_cic = NULL;
|
|
}
|
|
}
|
|
|
|
static inline void cfq_slice_expired(struct cfq_data *cfqd, int timed_out)
|
|
{
|
|
struct cfq_queue *cfqq = cfqd->active_queue;
|
|
|
|
if (cfqq)
|
|
__cfq_slice_expired(cfqd, cfqq, timed_out);
|
|
}
|
|
|
|
/*
|
|
* Get next queue for service. Unless we have a queue preemption,
|
|
* we'll simply select the first cfqq in the service tree.
|
|
*/
|
|
static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
|
|
{
|
|
if (RB_EMPTY_ROOT(&cfqd->service_tree.rb))
|
|
return NULL;
|
|
|
|
return cfq_rb_first(&cfqd->service_tree);
|
|
}
|
|
|
|
/*
|
|
* Get and set a new active queue for service.
|
|
*/
|
|
static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
|
|
struct cfq_queue *cfqq)
|
|
{
|
|
if (!cfqq) {
|
|
cfqq = cfq_get_next_queue(cfqd);
|
|
if (cfqq)
|
|
cfq_clear_cfqq_coop(cfqq);
|
|
}
|
|
|
|
__cfq_set_active_queue(cfqd, cfqq);
|
|
return cfqq;
|
|
}
|
|
|
|
static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
|
|
struct request *rq)
|
|
{
|
|
if (blk_rq_pos(rq) >= cfqd->last_position)
|
|
return blk_rq_pos(rq) - cfqd->last_position;
|
|
else
|
|
return cfqd->last_position - blk_rq_pos(rq);
|
|
}
|
|
|
|
#define CIC_SEEK_THR 8 * 1024
|
|
#define CIC_SEEKY(cic) ((cic)->seek_mean > CIC_SEEK_THR)
|
|
|
|
static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq)
|
|
{
|
|
struct cfq_io_context *cic = cfqd->active_cic;
|
|
sector_t sdist = cic->seek_mean;
|
|
|
|
if (!sample_valid(cic->seek_samples))
|
|
sdist = CIC_SEEK_THR;
|
|
|
|
return cfq_dist_from_last(cfqd, rq) <= sdist;
|
|
}
|
|
|
|
static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
|
|
struct cfq_queue *cur_cfqq)
|
|
{
|
|
struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
|
|
struct rb_node *parent, *node;
|
|
struct cfq_queue *__cfqq;
|
|
sector_t sector = cfqd->last_position;
|
|
|
|
if (RB_EMPTY_ROOT(root))
|
|
return NULL;
|
|
|
|
/*
|
|
* First, if we find a request starting at the end of the last
|
|
* request, choose it.
|
|
*/
|
|
__cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
|
|
if (__cfqq)
|
|
return __cfqq;
|
|
|
|
/*
|
|
* If the exact sector wasn't found, the parent of the NULL leaf
|
|
* will contain the closest sector.
|
|
*/
|
|
__cfqq = rb_entry(parent, struct cfq_queue, p_node);
|
|
if (cfq_rq_close(cfqd, __cfqq->next_rq))
|
|
return __cfqq;
|
|
|
|
if (blk_rq_pos(__cfqq->next_rq) < sector)
|
|
node = rb_next(&__cfqq->p_node);
|
|
else
|
|
node = rb_prev(&__cfqq->p_node);
|
|
if (!node)
|
|
return NULL;
|
|
|
|
__cfqq = rb_entry(node, struct cfq_queue, p_node);
|
|
if (cfq_rq_close(cfqd, __cfqq->next_rq))
|
|
return __cfqq;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* cfqd - obvious
|
|
* cur_cfqq - passed in so that we don't decide that the current queue is
|
|
* closely cooperating with itself.
|
|
*
|
|
* So, basically we're assuming that that cur_cfqq has dispatched at least
|
|
* one request, and that cfqd->last_position reflects a position on the disk
|
|
* associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
|
|
* assumption.
|
|
*/
|
|
static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
|
|
struct cfq_queue *cur_cfqq,
|
|
int probe)
|
|
{
|
|
struct cfq_queue *cfqq;
|
|
|
|
/*
|
|
* A valid cfq_io_context is necessary to compare requests against
|
|
* the seek_mean of the current cfqq.
|
|
*/
|
|
if (!cfqd->active_cic)
|
|
return NULL;
|
|
|
|
/*
|
|
* We should notice if some of the queues are cooperating, eg
|
|
* working closely on the same area of the disk. In that case,
|
|
* we can group them together and don't waste time idling.
|
|
*/
|
|
cfqq = cfqq_close(cfqd, cur_cfqq);
|
|
if (!cfqq)
|
|
return NULL;
|
|
|
|
if (cfq_cfqq_coop(cfqq))
|
|
return NULL;
|
|
|
|
if (!probe)
|
|
cfq_mark_cfqq_coop(cfqq);
|
|
return cfqq;
|
|
}
|
|
|
|
static void cfq_arm_slice_timer(struct cfq_data *cfqd)
|
|
{
|
|
struct cfq_queue *cfqq = cfqd->active_queue;
|
|
struct cfq_io_context *cic;
|
|
unsigned long sl;
|
|
|
|
/*
|
|
* SSD device without seek penalty, disable idling. But only do so
|
|
* for devices that support queuing, otherwise we still have a problem
|
|
* with sync vs async workloads.
|
|
*/
|
|
if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
|
|
return;
|
|
|
|
WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
|
|
WARN_ON(cfq_cfqq_slice_new(cfqq));
|
|
|
|
/*
|
|
* idle is disabled, either manually or by past process history
|
|
*/
|
|
if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq))
|
|
return;
|
|
|
|
/*
|
|
* still requests with the driver, don't idle
|
|
*/
|
|
if (cfqd->rq_in_driver)
|
|
return;
|
|
|
|
/*
|
|
* task has exited, don't wait
|
|
*/
|
|
cic = cfqd->active_cic;
|
|
if (!cic || !atomic_read(&cic->ioc->nr_tasks))
|
|
return;
|
|
|
|
cfq_mark_cfqq_wait_request(cfqq);
|
|
|
|
/*
|
|
* we don't want to idle for seeks, but we do want to allow
|
|
* fair distribution of slice time for a process doing back-to-back
|
|
* seeks. so allow a little bit of time for him to submit a new rq
|
|
*/
|
|
sl = cfqd->cfq_slice_idle;
|
|
if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic))
|
|
sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT));
|
|
|
|
mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
|
|
cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
|
|
}
|
|
|
|
/*
|
|
* Move request from internal lists to the request queue dispatch list.
|
|
*/
|
|
static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
|
|
cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
|
|
|
|
cfq_remove_request(rq);
|
|
cfqq->dispatched++;
|
|
elv_dispatch_sort(q, rq);
|
|
|
|
if (cfq_cfqq_sync(cfqq))
|
|
cfqd->sync_flight++;
|
|
}
|
|
|
|
/*
|
|
* return expired entry, or NULL to just start from scratch in rbtree
|
|
*/
|
|
static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
|
|
{
|
|
struct cfq_data *cfqd = cfqq->cfqd;
|
|
struct request *rq;
|
|
int fifo;
|
|
|
|
if (cfq_cfqq_fifo_expire(cfqq))
|
|
return NULL;
|
|
|
|
cfq_mark_cfqq_fifo_expire(cfqq);
|
|
|
|
if (list_empty(&cfqq->fifo))
|
|
return NULL;
|
|
|
|
fifo = cfq_cfqq_sync(cfqq);
|
|
rq = rq_entry_fifo(cfqq->fifo.next);
|
|
|
|
if (time_before(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo]))
|
|
rq = NULL;
|
|
|
|
cfq_log_cfqq(cfqd, cfqq, "fifo=%p", rq);
|
|
return rq;
|
|
}
|
|
|
|
static inline int
|
|
cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
const int base_rq = cfqd->cfq_slice_async_rq;
|
|
|
|
WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
|
|
|
|
return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
|
|
}
|
|
|
|
/*
|
|
* Select a queue for service. If we have a current active queue,
|
|
* check whether to continue servicing it, or retrieve and set a new one.
|
|
*/
|
|
static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
|
|
{
|
|
struct cfq_queue *cfqq, *new_cfqq = NULL;
|
|
|
|
cfqq = cfqd->active_queue;
|
|
if (!cfqq)
|
|
goto new_queue;
|
|
|
|
/*
|
|
* The active queue has run out of time, expire it and select new.
|
|
*/
|
|
if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq))
|
|
goto expire;
|
|
|
|
/*
|
|
* If we have a RT cfqq waiting, then we pre-empt the current non-rt
|
|
* cfqq.
|
|
*/
|
|
if (!cfq_class_rt(cfqq) && cfqd->busy_rt_queues) {
|
|
/*
|
|
* We simulate this as cfqq timed out so that it gets to bank
|
|
* the remaining of its time slice.
|
|
*/
|
|
cfq_log_cfqq(cfqd, cfqq, "preempt");
|
|
cfq_slice_expired(cfqd, 1);
|
|
goto new_queue;
|
|
}
|
|
|
|
/*
|
|
* The active queue has requests and isn't expired, allow it to
|
|
* dispatch.
|
|
*/
|
|
if (!RB_EMPTY_ROOT(&cfqq->sort_list))
|
|
goto keep_queue;
|
|
|
|
/*
|
|
* If another queue has a request waiting within our mean seek
|
|
* distance, let it run. The expire code will check for close
|
|
* cooperators and put the close queue at the front of the service
|
|
* tree.
|
|
*/
|
|
new_cfqq = cfq_close_cooperator(cfqd, cfqq, 0);
|
|
if (new_cfqq)
|
|
goto expire;
|
|
|
|
/*
|
|
* No requests pending. If the active queue still has requests in
|
|
* flight or is idling for a new request, allow either of these
|
|
* conditions to happen (or time out) before selecting a new queue.
|
|
*/
|
|
if (timer_pending(&cfqd->idle_slice_timer) ||
|
|
(cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) {
|
|
cfqq = NULL;
|
|
goto keep_queue;
|
|
}
|
|
|
|
expire:
|
|
cfq_slice_expired(cfqd, 0);
|
|
new_queue:
|
|
cfqq = cfq_set_active_queue(cfqd, new_cfqq);
|
|
keep_queue:
|
|
return cfqq;
|
|
}
|
|
|
|
static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
|
|
{
|
|
int dispatched = 0;
|
|
|
|
while (cfqq->next_rq) {
|
|
cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
|
|
dispatched++;
|
|
}
|
|
|
|
BUG_ON(!list_empty(&cfqq->fifo));
|
|
return dispatched;
|
|
}
|
|
|
|
/*
|
|
* Drain our current requests. Used for barriers and when switching
|
|
* io schedulers on-the-fly.
|
|
*/
|
|
static int cfq_forced_dispatch(struct cfq_data *cfqd)
|
|
{
|
|
struct cfq_queue *cfqq;
|
|
int dispatched = 0;
|
|
|
|
while ((cfqq = cfq_rb_first(&cfqd->service_tree)) != NULL)
|
|
dispatched += __cfq_forced_dispatch_cfqq(cfqq);
|
|
|
|
cfq_slice_expired(cfqd, 0);
|
|
|
|
BUG_ON(cfqd->busy_queues);
|
|
|
|
cfq_log(cfqd, "forced_dispatch=%d", dispatched);
|
|
return dispatched;
|
|
}
|
|
|
|
/*
|
|
* Dispatch a request from cfqq, moving them to the request queue
|
|
* dispatch list.
|
|
*/
|
|
static void cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
struct request *rq;
|
|
|
|
BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
|
|
|
|
/*
|
|
* follow expired path, else get first next available
|
|
*/
|
|
rq = cfq_check_fifo(cfqq);
|
|
if (!rq)
|
|
rq = cfqq->next_rq;
|
|
|
|
/*
|
|
* insert request into driver dispatch list
|
|
*/
|
|
cfq_dispatch_insert(cfqd->queue, rq);
|
|
|
|
if (!cfqd->active_cic) {
|
|
struct cfq_io_context *cic = RQ_CIC(rq);
|
|
|
|
atomic_long_inc(&cic->ioc->refcount);
|
|
cfqd->active_cic = cic;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Find the cfqq that we need to service and move a request from that to the
|
|
* dispatch list
|
|
*/
|
|
static int cfq_dispatch_requests(struct request_queue *q, int force)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_queue *cfqq;
|
|
unsigned int max_dispatch;
|
|
|
|
if (!cfqd->busy_queues)
|
|
return 0;
|
|
|
|
if (unlikely(force))
|
|
return cfq_forced_dispatch(cfqd);
|
|
|
|
cfqq = cfq_select_queue(cfqd);
|
|
if (!cfqq)
|
|
return 0;
|
|
|
|
/*
|
|
* If this is an async queue and we have sync IO in flight, let it wait
|
|
*/
|
|
if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq))
|
|
return 0;
|
|
|
|
max_dispatch = cfqd->cfq_quantum;
|
|
if (cfq_class_idle(cfqq))
|
|
max_dispatch = 1;
|
|
|
|
/*
|
|
* Does this cfqq already have too much IO in flight?
|
|
*/
|
|
if (cfqq->dispatched >= max_dispatch) {
|
|
/*
|
|
* idle queue must always only have a single IO in flight
|
|
*/
|
|
if (cfq_class_idle(cfqq))
|
|
return 0;
|
|
|
|
/*
|
|
* We have other queues, don't allow more IO from this one
|
|
*/
|
|
if (cfqd->busy_queues > 1)
|
|
return 0;
|
|
|
|
/*
|
|
* we are the only queue, allow up to 4 times of 'quantum'
|
|
*/
|
|
if (cfqq->dispatched >= 4 * max_dispatch)
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Dispatch a request from this cfqq
|
|
*/
|
|
cfq_dispatch_request(cfqd, cfqq);
|
|
cfqq->slice_dispatch++;
|
|
cfq_clear_cfqq_must_dispatch(cfqq);
|
|
|
|
/*
|
|
* expire an async queue immediately if it has used up its slice. idle
|
|
* queue always expire after 1 dispatch round.
|
|
*/
|
|
if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
|
|
cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
|
|
cfq_class_idle(cfqq))) {
|
|
cfqq->slice_end = jiffies + 1;
|
|
cfq_slice_expired(cfqd, 0);
|
|
}
|
|
|
|
cfq_log(cfqd, "dispatched a request");
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* task holds one reference to the queue, dropped when task exits. each rq
|
|
* in-flight on this queue also holds a reference, dropped when rq is freed.
|
|
*
|
|
* queue lock must be held here.
|
|
*/
|
|
static void cfq_put_queue(struct cfq_queue *cfqq)
|
|
{
|
|
struct cfq_data *cfqd = cfqq->cfqd;
|
|
|
|
BUG_ON(atomic_read(&cfqq->ref) <= 0);
|
|
|
|
if (!atomic_dec_and_test(&cfqq->ref))
|
|
return;
|
|
|
|
cfq_log_cfqq(cfqd, cfqq, "put_queue");
|
|
BUG_ON(rb_first(&cfqq->sort_list));
|
|
BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
|
|
BUG_ON(cfq_cfqq_on_rr(cfqq));
|
|
|
|
if (unlikely(cfqd->active_queue == cfqq)) {
|
|
__cfq_slice_expired(cfqd, cfqq, 0);
|
|
cfq_schedule_dispatch(cfqd);
|
|
}
|
|
|
|
kmem_cache_free(cfq_pool, cfqq);
|
|
}
|
|
|
|
/*
|
|
* Must always be called with the rcu_read_lock() held
|
|
*/
|
|
static void
|
|
__call_for_each_cic(struct io_context *ioc,
|
|
void (*func)(struct io_context *, struct cfq_io_context *))
|
|
{
|
|
struct cfq_io_context *cic;
|
|
struct hlist_node *n;
|
|
|
|
hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
|
|
func(ioc, cic);
|
|
}
|
|
|
|
/*
|
|
* Call func for each cic attached to this ioc.
|
|
*/
|
|
static void
|
|
call_for_each_cic(struct io_context *ioc,
|
|
void (*func)(struct io_context *, struct cfq_io_context *))
|
|
{
|
|
rcu_read_lock();
|
|
__call_for_each_cic(ioc, func);
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
static void cfq_cic_free_rcu(struct rcu_head *head)
|
|
{
|
|
struct cfq_io_context *cic;
|
|
|
|
cic = container_of(head, struct cfq_io_context, rcu_head);
|
|
|
|
kmem_cache_free(cfq_ioc_pool, cic);
|
|
elv_ioc_count_dec(ioc_count);
|
|
|
|
if (ioc_gone) {
|
|
/*
|
|
* CFQ scheduler is exiting, grab exit lock and check
|
|
* the pending io context count. If it hits zero,
|
|
* complete ioc_gone and set it back to NULL
|
|
*/
|
|
spin_lock(&ioc_gone_lock);
|
|
if (ioc_gone && !elv_ioc_count_read(ioc_count)) {
|
|
complete(ioc_gone);
|
|
ioc_gone = NULL;
|
|
}
|
|
spin_unlock(&ioc_gone_lock);
|
|
}
|
|
}
|
|
|
|
static void cfq_cic_free(struct cfq_io_context *cic)
|
|
{
|
|
call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
|
|
}
|
|
|
|
static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
|
|
{
|
|
unsigned long flags;
|
|
|
|
BUG_ON(!cic->dead_key);
|
|
|
|
spin_lock_irqsave(&ioc->lock, flags);
|
|
radix_tree_delete(&ioc->radix_root, cic->dead_key);
|
|
hlist_del_rcu(&cic->cic_list);
|
|
spin_unlock_irqrestore(&ioc->lock, flags);
|
|
|
|
cfq_cic_free(cic);
|
|
}
|
|
|
|
/*
|
|
* Must be called with rcu_read_lock() held or preemption otherwise disabled.
|
|
* Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
|
|
* and ->trim() which is called with the task lock held
|
|
*/
|
|
static void cfq_free_io_context(struct io_context *ioc)
|
|
{
|
|
/*
|
|
* ioc->refcount is zero here, or we are called from elv_unregister(),
|
|
* so no more cic's are allowed to be linked into this ioc. So it
|
|
* should be ok to iterate over the known list, we will see all cic's
|
|
* since no new ones are added.
|
|
*/
|
|
__call_for_each_cic(ioc, cic_free_func);
|
|
}
|
|
|
|
static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
if (unlikely(cfqq == cfqd->active_queue)) {
|
|
__cfq_slice_expired(cfqd, cfqq, 0);
|
|
cfq_schedule_dispatch(cfqd);
|
|
}
|
|
|
|
cfq_put_queue(cfqq);
|
|
}
|
|
|
|
static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
|
|
struct cfq_io_context *cic)
|
|
{
|
|
struct io_context *ioc = cic->ioc;
|
|
|
|
list_del_init(&cic->queue_list);
|
|
|
|
/*
|
|
* Make sure key == NULL is seen for dead queues
|
|
*/
|
|
smp_wmb();
|
|
cic->dead_key = (unsigned long) cic->key;
|
|
cic->key = NULL;
|
|
|
|
if (ioc->ioc_data == cic)
|
|
rcu_assign_pointer(ioc->ioc_data, NULL);
|
|
|
|
if (cic->cfqq[BLK_RW_ASYNC]) {
|
|
cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
|
|
cic->cfqq[BLK_RW_ASYNC] = NULL;
|
|
}
|
|
|
|
if (cic->cfqq[BLK_RW_SYNC]) {
|
|
cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
|
|
cic->cfqq[BLK_RW_SYNC] = NULL;
|
|
}
|
|
}
|
|
|
|
static void cfq_exit_single_io_context(struct io_context *ioc,
|
|
struct cfq_io_context *cic)
|
|
{
|
|
struct cfq_data *cfqd = cic->key;
|
|
|
|
if (cfqd) {
|
|
struct request_queue *q = cfqd->queue;
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
|
|
/*
|
|
* Ensure we get a fresh copy of the ->key to prevent
|
|
* race between exiting task and queue
|
|
*/
|
|
smp_read_barrier_depends();
|
|
if (cic->key)
|
|
__cfq_exit_single_io_context(cfqd, cic);
|
|
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The process that ioc belongs to has exited, we need to clean up
|
|
* and put the internal structures we have that belongs to that process.
|
|
*/
|
|
static void cfq_exit_io_context(struct io_context *ioc)
|
|
{
|
|
call_for_each_cic(ioc, cfq_exit_single_io_context);
|
|
}
|
|
|
|
static struct cfq_io_context *
|
|
cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
|
|
{
|
|
struct cfq_io_context *cic;
|
|
|
|
cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
|
|
cfqd->queue->node);
|
|
if (cic) {
|
|
cic->last_end_request = jiffies;
|
|
INIT_LIST_HEAD(&cic->queue_list);
|
|
INIT_HLIST_NODE(&cic->cic_list);
|
|
cic->dtor = cfq_free_io_context;
|
|
cic->exit = cfq_exit_io_context;
|
|
elv_ioc_count_inc(ioc_count);
|
|
}
|
|
|
|
return cic;
|
|
}
|
|
|
|
static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
int ioprio_class;
|
|
|
|
if (!cfq_cfqq_prio_changed(cfqq))
|
|
return;
|
|
|
|
ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
|
|
switch (ioprio_class) {
|
|
default:
|
|
printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
|
|
case IOPRIO_CLASS_NONE:
|
|
/*
|
|
* no prio set, inherit CPU scheduling settings
|
|
*/
|
|
cfqq->ioprio = task_nice_ioprio(tsk);
|
|
cfqq->ioprio_class = task_nice_ioclass(tsk);
|
|
break;
|
|
case IOPRIO_CLASS_RT:
|
|
cfqq->ioprio = task_ioprio(ioc);
|
|
cfqq->ioprio_class = IOPRIO_CLASS_RT;
|
|
break;
|
|
case IOPRIO_CLASS_BE:
|
|
cfqq->ioprio = task_ioprio(ioc);
|
|
cfqq->ioprio_class = IOPRIO_CLASS_BE;
|
|
break;
|
|
case IOPRIO_CLASS_IDLE:
|
|
cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
|
|
cfqq->ioprio = 7;
|
|
cfq_clear_cfqq_idle_window(cfqq);
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* keep track of original prio settings in case we have to temporarily
|
|
* elevate the priority of this queue
|
|
*/
|
|
cfqq->org_ioprio = cfqq->ioprio;
|
|
cfqq->org_ioprio_class = cfqq->ioprio_class;
|
|
cfq_clear_cfqq_prio_changed(cfqq);
|
|
}
|
|
|
|
static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
|
|
{
|
|
struct cfq_data *cfqd = cic->key;
|
|
struct cfq_queue *cfqq;
|
|
unsigned long flags;
|
|
|
|
if (unlikely(!cfqd))
|
|
return;
|
|
|
|
spin_lock_irqsave(cfqd->queue->queue_lock, flags);
|
|
|
|
cfqq = cic->cfqq[BLK_RW_ASYNC];
|
|
if (cfqq) {
|
|
struct cfq_queue *new_cfqq;
|
|
new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
|
|
GFP_ATOMIC);
|
|
if (new_cfqq) {
|
|
cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
|
|
cfq_put_queue(cfqq);
|
|
}
|
|
}
|
|
|
|
cfqq = cic->cfqq[BLK_RW_SYNC];
|
|
if (cfqq)
|
|
cfq_mark_cfqq_prio_changed(cfqq);
|
|
|
|
spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
|
|
}
|
|
|
|
static void cfq_ioc_set_ioprio(struct io_context *ioc)
|
|
{
|
|
call_for_each_cic(ioc, changed_ioprio);
|
|
ioc->ioprio_changed = 0;
|
|
}
|
|
|
|
static struct cfq_queue *
|
|
cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync,
|
|
struct io_context *ioc, gfp_t gfp_mask)
|
|
{
|
|
struct cfq_queue *cfqq, *new_cfqq = NULL;
|
|
struct cfq_io_context *cic;
|
|
|
|
retry:
|
|
cic = cfq_cic_lookup(cfqd, ioc);
|
|
/* cic always exists here */
|
|
cfqq = cic_to_cfqq(cic, is_sync);
|
|
|
|
if (!cfqq) {
|
|
if (new_cfqq) {
|
|
cfqq = new_cfqq;
|
|
new_cfqq = NULL;
|
|
} else if (gfp_mask & __GFP_WAIT) {
|
|
/*
|
|
* Inform the allocator of the fact that we will
|
|
* just repeat this allocation if it fails, to allow
|
|
* the allocator to do whatever it needs to attempt to
|
|
* free memory.
|
|
*/
|
|
spin_unlock_irq(cfqd->queue->queue_lock);
|
|
new_cfqq = kmem_cache_alloc_node(cfq_pool,
|
|
gfp_mask | __GFP_NOFAIL | __GFP_ZERO,
|
|
cfqd->queue->node);
|
|
spin_lock_irq(cfqd->queue->queue_lock);
|
|
goto retry;
|
|
} else {
|
|
cfqq = kmem_cache_alloc_node(cfq_pool,
|
|
gfp_mask | __GFP_ZERO,
|
|
cfqd->queue->node);
|
|
if (!cfqq)
|
|
goto out;
|
|
}
|
|
|
|
RB_CLEAR_NODE(&cfqq->rb_node);
|
|
RB_CLEAR_NODE(&cfqq->p_node);
|
|
INIT_LIST_HEAD(&cfqq->fifo);
|
|
|
|
atomic_set(&cfqq->ref, 0);
|
|
cfqq->cfqd = cfqd;
|
|
|
|
cfq_mark_cfqq_prio_changed(cfqq);
|
|
|
|
cfq_init_prio_data(cfqq, ioc);
|
|
|
|
if (is_sync) {
|
|
if (!cfq_class_idle(cfqq))
|
|
cfq_mark_cfqq_idle_window(cfqq);
|
|
cfq_mark_cfqq_sync(cfqq);
|
|
}
|
|
cfqq->pid = current->pid;
|
|
cfq_log_cfqq(cfqd, cfqq, "alloced");
|
|
}
|
|
|
|
if (new_cfqq)
|
|
kmem_cache_free(cfq_pool, new_cfqq);
|
|
|
|
out:
|
|
WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq);
|
|
return cfqq;
|
|
}
|
|
|
|
static struct cfq_queue **
|
|
cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
|
|
{
|
|
switch (ioprio_class) {
|
|
case IOPRIO_CLASS_RT:
|
|
return &cfqd->async_cfqq[0][ioprio];
|
|
case IOPRIO_CLASS_BE:
|
|
return &cfqd->async_cfqq[1][ioprio];
|
|
case IOPRIO_CLASS_IDLE:
|
|
return &cfqd->async_idle_cfqq;
|
|
default:
|
|
BUG();
|
|
}
|
|
}
|
|
|
|
static struct cfq_queue *
|
|
cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc,
|
|
gfp_t gfp_mask)
|
|
{
|
|
const int ioprio = task_ioprio(ioc);
|
|
const int ioprio_class = task_ioprio_class(ioc);
|
|
struct cfq_queue **async_cfqq = NULL;
|
|
struct cfq_queue *cfqq = NULL;
|
|
|
|
if (!is_sync) {
|
|
async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
|
|
cfqq = *async_cfqq;
|
|
}
|
|
|
|
if (!cfqq) {
|
|
cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
|
|
if (!cfqq)
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* pin the queue now that it's allocated, scheduler exit will prune it
|
|
*/
|
|
if (!is_sync && !(*async_cfqq)) {
|
|
atomic_inc(&cfqq->ref);
|
|
*async_cfqq = cfqq;
|
|
}
|
|
|
|
atomic_inc(&cfqq->ref);
|
|
return cfqq;
|
|
}
|
|
|
|
/*
|
|
* We drop cfq io contexts lazily, so we may find a dead one.
|
|
*/
|
|
static void
|
|
cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
|
|
struct cfq_io_context *cic)
|
|
{
|
|
unsigned long flags;
|
|
|
|
WARN_ON(!list_empty(&cic->queue_list));
|
|
|
|
spin_lock_irqsave(&ioc->lock, flags);
|
|
|
|
BUG_ON(ioc->ioc_data == cic);
|
|
|
|
radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd);
|
|
hlist_del_rcu(&cic->cic_list);
|
|
spin_unlock_irqrestore(&ioc->lock, flags);
|
|
|
|
cfq_cic_free(cic);
|
|
}
|
|
|
|
static struct cfq_io_context *
|
|
cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
|
|
{
|
|
struct cfq_io_context *cic;
|
|
unsigned long flags;
|
|
void *k;
|
|
|
|
if (unlikely(!ioc))
|
|
return NULL;
|
|
|
|
rcu_read_lock();
|
|
|
|
/*
|
|
* we maintain a last-hit cache, to avoid browsing over the tree
|
|
*/
|
|
cic = rcu_dereference(ioc->ioc_data);
|
|
if (cic && cic->key == cfqd) {
|
|
rcu_read_unlock();
|
|
return cic;
|
|
}
|
|
|
|
do {
|
|
cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd);
|
|
rcu_read_unlock();
|
|
if (!cic)
|
|
break;
|
|
/* ->key must be copied to avoid race with cfq_exit_queue() */
|
|
k = cic->key;
|
|
if (unlikely(!k)) {
|
|
cfq_drop_dead_cic(cfqd, ioc, cic);
|
|
rcu_read_lock();
|
|
continue;
|
|
}
|
|
|
|
spin_lock_irqsave(&ioc->lock, flags);
|
|
rcu_assign_pointer(ioc->ioc_data, cic);
|
|
spin_unlock_irqrestore(&ioc->lock, flags);
|
|
break;
|
|
} while (1);
|
|
|
|
return cic;
|
|
}
|
|
|
|
/*
|
|
* Add cic into ioc, using cfqd as the search key. This enables us to lookup
|
|
* the process specific cfq io context when entered from the block layer.
|
|
* Also adds the cic to a per-cfqd list, used when this queue is removed.
|
|
*/
|
|
static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
|
|
struct cfq_io_context *cic, gfp_t gfp_mask)
|
|
{
|
|
unsigned long flags;
|
|
int ret;
|
|
|
|
ret = radix_tree_preload(gfp_mask);
|
|
if (!ret) {
|
|
cic->ioc = ioc;
|
|
cic->key = cfqd;
|
|
|
|
spin_lock_irqsave(&ioc->lock, flags);
|
|
ret = radix_tree_insert(&ioc->radix_root,
|
|
(unsigned long) cfqd, cic);
|
|
if (!ret)
|
|
hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
|
|
spin_unlock_irqrestore(&ioc->lock, flags);
|
|
|
|
radix_tree_preload_end();
|
|
|
|
if (!ret) {
|
|
spin_lock_irqsave(cfqd->queue->queue_lock, flags);
|
|
list_add(&cic->queue_list, &cfqd->cic_list);
|
|
spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
|
|
}
|
|
}
|
|
|
|
if (ret)
|
|
printk(KERN_ERR "cfq: cic link failed!\n");
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Setup general io context and cfq io context. There can be several cfq
|
|
* io contexts per general io context, if this process is doing io to more
|
|
* than one device managed by cfq.
|
|
*/
|
|
static struct cfq_io_context *
|
|
cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
|
|
{
|
|
struct io_context *ioc = NULL;
|
|
struct cfq_io_context *cic;
|
|
|
|
might_sleep_if(gfp_mask & __GFP_WAIT);
|
|
|
|
ioc = get_io_context(gfp_mask, cfqd->queue->node);
|
|
if (!ioc)
|
|
return NULL;
|
|
|
|
cic = cfq_cic_lookup(cfqd, ioc);
|
|
if (cic)
|
|
goto out;
|
|
|
|
cic = cfq_alloc_io_context(cfqd, gfp_mask);
|
|
if (cic == NULL)
|
|
goto err;
|
|
|
|
if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
|
|
goto err_free;
|
|
|
|
out:
|
|
smp_read_barrier_depends();
|
|
if (unlikely(ioc->ioprio_changed))
|
|
cfq_ioc_set_ioprio(ioc);
|
|
|
|
return cic;
|
|
err_free:
|
|
cfq_cic_free(cic);
|
|
err:
|
|
put_io_context(ioc);
|
|
return NULL;
|
|
}
|
|
|
|
static void
|
|
cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
|
|
{
|
|
unsigned long elapsed = jiffies - cic->last_end_request;
|
|
unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
|
|
|
|
cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
|
|
cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
|
|
cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
|
|
}
|
|
|
|
static void
|
|
cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic,
|
|
struct request *rq)
|
|
{
|
|
sector_t sdist;
|
|
u64 total;
|
|
|
|
if (!cic->last_request_pos)
|
|
sdist = 0;
|
|
else if (cic->last_request_pos < blk_rq_pos(rq))
|
|
sdist = blk_rq_pos(rq) - cic->last_request_pos;
|
|
else
|
|
sdist = cic->last_request_pos - blk_rq_pos(rq);
|
|
|
|
/*
|
|
* Don't allow the seek distance to get too large from the
|
|
* odd fragment, pagein, etc
|
|
*/
|
|
if (cic->seek_samples <= 60) /* second&third seek */
|
|
sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024);
|
|
else
|
|
sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64);
|
|
|
|
cic->seek_samples = (7*cic->seek_samples + 256) / 8;
|
|
cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8;
|
|
total = cic->seek_total + (cic->seek_samples/2);
|
|
do_div(total, cic->seek_samples);
|
|
cic->seek_mean = (sector_t)total;
|
|
}
|
|
|
|
/*
|
|
* Disable idle window if the process thinks too long or seeks so much that
|
|
* it doesn't matter
|
|
*/
|
|
static void
|
|
cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
|
|
struct cfq_io_context *cic)
|
|
{
|
|
int old_idle, enable_idle;
|
|
|
|
/*
|
|
* Don't idle for async or idle io prio class
|
|
*/
|
|
if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
|
|
return;
|
|
|
|
enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
|
|
|
|
if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
|
|
(cfqd->hw_tag && CIC_SEEKY(cic)))
|
|
enable_idle = 0;
|
|
else if (sample_valid(cic->ttime_samples)) {
|
|
if (cic->ttime_mean > cfqd->cfq_slice_idle)
|
|
enable_idle = 0;
|
|
else
|
|
enable_idle = 1;
|
|
}
|
|
|
|
if (old_idle != enable_idle) {
|
|
cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
|
|
if (enable_idle)
|
|
cfq_mark_cfqq_idle_window(cfqq);
|
|
else
|
|
cfq_clear_cfqq_idle_window(cfqq);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Check if new_cfqq should preempt the currently active queue. Return 0 for
|
|
* no or if we aren't sure, a 1 will cause a preempt.
|
|
*/
|
|
static int
|
|
cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
|
|
struct request *rq)
|
|
{
|
|
struct cfq_queue *cfqq;
|
|
|
|
cfqq = cfqd->active_queue;
|
|
if (!cfqq)
|
|
return 0;
|
|
|
|
if (cfq_slice_used(cfqq))
|
|
return 1;
|
|
|
|
if (cfq_class_idle(new_cfqq))
|
|
return 0;
|
|
|
|
if (cfq_class_idle(cfqq))
|
|
return 1;
|
|
|
|
/*
|
|
* if the new request is sync, but the currently running queue is
|
|
* not, let the sync request have priority.
|
|
*/
|
|
if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
|
|
return 1;
|
|
|
|
/*
|
|
* So both queues are sync. Let the new request get disk time if
|
|
* it's a metadata request and the current queue is doing regular IO.
|
|
*/
|
|
if (rq_is_meta(rq) && !cfqq->meta_pending)
|
|
return 1;
|
|
|
|
/*
|
|
* Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
|
|
*/
|
|
if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
|
|
return 1;
|
|
|
|
if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
|
|
return 0;
|
|
|
|
/*
|
|
* if this request is as-good as one we would expect from the
|
|
* current cfqq, let it preempt
|
|
*/
|
|
if (cfq_rq_close(cfqd, rq))
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* cfqq preempts the active queue. if we allowed preempt with no slice left,
|
|
* let it have half of its nominal slice.
|
|
*/
|
|
static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
cfq_log_cfqq(cfqd, cfqq, "preempt");
|
|
cfq_slice_expired(cfqd, 1);
|
|
|
|
/*
|
|
* Put the new queue at the front of the of the current list,
|
|
* so we know that it will be selected next.
|
|
*/
|
|
BUG_ON(!cfq_cfqq_on_rr(cfqq));
|
|
|
|
cfq_service_tree_add(cfqd, cfqq, 1);
|
|
|
|
cfqq->slice_end = 0;
|
|
cfq_mark_cfqq_slice_new(cfqq);
|
|
}
|
|
|
|
/*
|
|
* Called when a new fs request (rq) is added (to cfqq). Check if there's
|
|
* something we should do about it
|
|
*/
|
|
static void
|
|
cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
|
|
struct request *rq)
|
|
{
|
|
struct cfq_io_context *cic = RQ_CIC(rq);
|
|
|
|
cfqd->rq_queued++;
|
|
if (rq_is_meta(rq))
|
|
cfqq->meta_pending++;
|
|
|
|
cfq_update_io_thinktime(cfqd, cic);
|
|
cfq_update_io_seektime(cfqd, cic, rq);
|
|
cfq_update_idle_window(cfqd, cfqq, cic);
|
|
|
|
cic->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
|
|
|
|
if (cfqq == cfqd->active_queue) {
|
|
/*
|
|
* Remember that we saw a request from this process, but
|
|
* don't start queuing just yet. Otherwise we risk seeing lots
|
|
* of tiny requests, because we disrupt the normal plugging
|
|
* and merging. If the request is already larger than a single
|
|
* page, let it rip immediately. For that case we assume that
|
|
* merging is already done. Ditto for a busy system that
|
|
* has other work pending, don't risk delaying until the
|
|
* idle timer unplug to continue working.
|
|
*/
|
|
if (cfq_cfqq_wait_request(cfqq)) {
|
|
if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
|
|
cfqd->busy_queues > 1) {
|
|
del_timer(&cfqd->idle_slice_timer);
|
|
__blk_run_queue(cfqd->queue);
|
|
}
|
|
cfq_mark_cfqq_must_dispatch(cfqq);
|
|
}
|
|
} else if (cfq_should_preempt(cfqd, cfqq, rq)) {
|
|
/*
|
|
* not the active queue - expire current slice if it is
|
|
* idle and has expired it's mean thinktime or this new queue
|
|
* has some old slice time left and is of higher priority or
|
|
* this new queue is RT and the current one is BE
|
|
*/
|
|
cfq_preempt_queue(cfqd, cfqq);
|
|
__blk_run_queue(cfqd->queue);
|
|
}
|
|
}
|
|
|
|
static void cfq_insert_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
|
|
cfq_log_cfqq(cfqd, cfqq, "insert_request");
|
|
cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
|
|
|
|
cfq_add_rq_rb(rq);
|
|
|
|
list_add_tail(&rq->queuelist, &cfqq->fifo);
|
|
|
|
cfq_rq_enqueued(cfqd, cfqq, rq);
|
|
}
|
|
|
|
/*
|
|
* Update hw_tag based on peak queue depth over 50 samples under
|
|
* sufficient load.
|
|
*/
|
|
static void cfq_update_hw_tag(struct cfq_data *cfqd)
|
|
{
|
|
if (cfqd->rq_in_driver > cfqd->rq_in_driver_peak)
|
|
cfqd->rq_in_driver_peak = cfqd->rq_in_driver;
|
|
|
|
if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
|
|
cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
|
|
return;
|
|
|
|
if (cfqd->hw_tag_samples++ < 50)
|
|
return;
|
|
|
|
if (cfqd->rq_in_driver_peak >= CFQ_HW_QUEUE_MIN)
|
|
cfqd->hw_tag = 1;
|
|
else
|
|
cfqd->hw_tag = 0;
|
|
|
|
cfqd->hw_tag_samples = 0;
|
|
cfqd->rq_in_driver_peak = 0;
|
|
}
|
|
|
|
static void cfq_completed_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
struct cfq_data *cfqd = cfqq->cfqd;
|
|
const int sync = rq_is_sync(rq);
|
|
unsigned long now;
|
|
|
|
now = jiffies;
|
|
cfq_log_cfqq(cfqd, cfqq, "complete");
|
|
|
|
cfq_update_hw_tag(cfqd);
|
|
|
|
WARN_ON(!cfqd->rq_in_driver);
|
|
WARN_ON(!cfqq->dispatched);
|
|
cfqd->rq_in_driver--;
|
|
cfqq->dispatched--;
|
|
|
|
if (cfq_cfqq_sync(cfqq))
|
|
cfqd->sync_flight--;
|
|
|
|
if (sync)
|
|
RQ_CIC(rq)->last_end_request = now;
|
|
|
|
/*
|
|
* If this is the active queue, check if it needs to be expired,
|
|
* or if we want to idle in case it has no pending requests.
|
|
*/
|
|
if (cfqd->active_queue == cfqq) {
|
|
const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
|
|
|
|
if (cfq_cfqq_slice_new(cfqq)) {
|
|
cfq_set_prio_slice(cfqd, cfqq);
|
|
cfq_clear_cfqq_slice_new(cfqq);
|
|
}
|
|
/*
|
|
* If there are no requests waiting in this queue, and
|
|
* there are other queues ready to issue requests, AND
|
|
* those other queues are issuing requests within our
|
|
* mean seek distance, give them a chance to run instead
|
|
* of idling.
|
|
*/
|
|
if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
|
|
cfq_slice_expired(cfqd, 1);
|
|
else if (cfqq_empty && !cfq_close_cooperator(cfqd, cfqq, 1) &&
|
|
sync && !rq_noidle(rq))
|
|
cfq_arm_slice_timer(cfqd);
|
|
}
|
|
|
|
if (!cfqd->rq_in_driver)
|
|
cfq_schedule_dispatch(cfqd);
|
|
}
|
|
|
|
/*
|
|
* we temporarily boost lower priority queues if they are holding fs exclusive
|
|
* resources. they are boosted to normal prio (CLASS_BE/4)
|
|
*/
|
|
static void cfq_prio_boost(struct cfq_queue *cfqq)
|
|
{
|
|
if (has_fs_excl()) {
|
|
/*
|
|
* boost idle prio on transactions that would lock out other
|
|
* users of the filesystem
|
|
*/
|
|
if (cfq_class_idle(cfqq))
|
|
cfqq->ioprio_class = IOPRIO_CLASS_BE;
|
|
if (cfqq->ioprio > IOPRIO_NORM)
|
|
cfqq->ioprio = IOPRIO_NORM;
|
|
} else {
|
|
/*
|
|
* check if we need to unboost the queue
|
|
*/
|
|
if (cfqq->ioprio_class != cfqq->org_ioprio_class)
|
|
cfqq->ioprio_class = cfqq->org_ioprio_class;
|
|
if (cfqq->ioprio != cfqq->org_ioprio)
|
|
cfqq->ioprio = cfqq->org_ioprio;
|
|
}
|
|
}
|
|
|
|
static inline int __cfq_may_queue(struct cfq_queue *cfqq)
|
|
{
|
|
if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) &&
|
|
!cfq_cfqq_must_alloc_slice(cfqq)) {
|
|
cfq_mark_cfqq_must_alloc_slice(cfqq);
|
|
return ELV_MQUEUE_MUST;
|
|
}
|
|
|
|
return ELV_MQUEUE_MAY;
|
|
}
|
|
|
|
static int cfq_may_queue(struct request_queue *q, int rw)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct task_struct *tsk = current;
|
|
struct cfq_io_context *cic;
|
|
struct cfq_queue *cfqq;
|
|
|
|
/*
|
|
* don't force setup of a queue from here, as a call to may_queue
|
|
* does not necessarily imply that a request actually will be queued.
|
|
* so just lookup a possibly existing queue, or return 'may queue'
|
|
* if that fails
|
|
*/
|
|
cic = cfq_cic_lookup(cfqd, tsk->io_context);
|
|
if (!cic)
|
|
return ELV_MQUEUE_MAY;
|
|
|
|
cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
|
|
if (cfqq) {
|
|
cfq_init_prio_data(cfqq, cic->ioc);
|
|
cfq_prio_boost(cfqq);
|
|
|
|
return __cfq_may_queue(cfqq);
|
|
}
|
|
|
|
return ELV_MQUEUE_MAY;
|
|
}
|
|
|
|
/*
|
|
* queue lock held here
|
|
*/
|
|
static void cfq_put_request(struct request *rq)
|
|
{
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
|
|
if (cfqq) {
|
|
const int rw = rq_data_dir(rq);
|
|
|
|
BUG_ON(!cfqq->allocated[rw]);
|
|
cfqq->allocated[rw]--;
|
|
|
|
put_io_context(RQ_CIC(rq)->ioc);
|
|
|
|
rq->elevator_private = NULL;
|
|
rq->elevator_private2 = NULL;
|
|
|
|
cfq_put_queue(cfqq);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Allocate cfq data structures associated with this request.
|
|
*/
|
|
static int
|
|
cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_io_context *cic;
|
|
const int rw = rq_data_dir(rq);
|
|
const int is_sync = rq_is_sync(rq);
|
|
struct cfq_queue *cfqq;
|
|
unsigned long flags;
|
|
|
|
might_sleep_if(gfp_mask & __GFP_WAIT);
|
|
|
|
cic = cfq_get_io_context(cfqd, gfp_mask);
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
|
|
if (!cic)
|
|
goto queue_fail;
|
|
|
|
cfqq = cic_to_cfqq(cic, is_sync);
|
|
if (!cfqq) {
|
|
cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
|
|
|
|
if (!cfqq)
|
|
goto queue_fail;
|
|
|
|
cic_set_cfqq(cic, cfqq, is_sync);
|
|
}
|
|
|
|
cfqq->allocated[rw]++;
|
|
cfq_clear_cfqq_must_alloc(cfqq);
|
|
atomic_inc(&cfqq->ref);
|
|
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
|
|
rq->elevator_private = cic;
|
|
rq->elevator_private2 = cfqq;
|
|
return 0;
|
|
|
|
queue_fail:
|
|
if (cic)
|
|
put_io_context(cic->ioc);
|
|
|
|
cfq_schedule_dispatch(cfqd);
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
cfq_log(cfqd, "set_request fail");
|
|
return 1;
|
|
}
|
|
|
|
static void cfq_kick_queue(struct work_struct *work)
|
|
{
|
|
struct cfq_data *cfqd =
|
|
container_of(work, struct cfq_data, unplug_work);
|
|
struct request_queue *q = cfqd->queue;
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
__blk_run_queue(cfqd->queue);
|
|
spin_unlock_irq(q->queue_lock);
|
|
}
|
|
|
|
/*
|
|
* Timer running if the active_queue is currently idling inside its time slice
|
|
*/
|
|
static void cfq_idle_slice_timer(unsigned long data)
|
|
{
|
|
struct cfq_data *cfqd = (struct cfq_data *) data;
|
|
struct cfq_queue *cfqq;
|
|
unsigned long flags;
|
|
int timed_out = 1;
|
|
|
|
cfq_log(cfqd, "idle timer fired");
|
|
|
|
spin_lock_irqsave(cfqd->queue->queue_lock, flags);
|
|
|
|
cfqq = cfqd->active_queue;
|
|
if (cfqq) {
|
|
timed_out = 0;
|
|
|
|
/*
|
|
* We saw a request before the queue expired, let it through
|
|
*/
|
|
if (cfq_cfqq_must_dispatch(cfqq))
|
|
goto out_kick;
|
|
|
|
/*
|
|
* expired
|
|
*/
|
|
if (cfq_slice_used(cfqq))
|
|
goto expire;
|
|
|
|
/*
|
|
* only expire and reinvoke request handler, if there are
|
|
* other queues with pending requests
|
|
*/
|
|
if (!cfqd->busy_queues)
|
|
goto out_cont;
|
|
|
|
/*
|
|
* not expired and it has a request pending, let it dispatch
|
|
*/
|
|
if (!RB_EMPTY_ROOT(&cfqq->sort_list))
|
|
goto out_kick;
|
|
}
|
|
expire:
|
|
cfq_slice_expired(cfqd, timed_out);
|
|
out_kick:
|
|
cfq_schedule_dispatch(cfqd);
|
|
out_cont:
|
|
spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
|
|
}
|
|
|
|
static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
|
|
{
|
|
del_timer_sync(&cfqd->idle_slice_timer);
|
|
cancel_work_sync(&cfqd->unplug_work);
|
|
}
|
|
|
|
static void cfq_put_async_queues(struct cfq_data *cfqd)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < IOPRIO_BE_NR; i++) {
|
|
if (cfqd->async_cfqq[0][i])
|
|
cfq_put_queue(cfqd->async_cfqq[0][i]);
|
|
if (cfqd->async_cfqq[1][i])
|
|
cfq_put_queue(cfqd->async_cfqq[1][i]);
|
|
}
|
|
|
|
if (cfqd->async_idle_cfqq)
|
|
cfq_put_queue(cfqd->async_idle_cfqq);
|
|
}
|
|
|
|
static void cfq_exit_queue(struct elevator_queue *e)
|
|
{
|
|
struct cfq_data *cfqd = e->elevator_data;
|
|
struct request_queue *q = cfqd->queue;
|
|
|
|
cfq_shutdown_timer_wq(cfqd);
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
|
|
if (cfqd->active_queue)
|
|
__cfq_slice_expired(cfqd, cfqd->active_queue, 0);
|
|
|
|
while (!list_empty(&cfqd->cic_list)) {
|
|
struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
|
|
struct cfq_io_context,
|
|
queue_list);
|
|
|
|
__cfq_exit_single_io_context(cfqd, cic);
|
|
}
|
|
|
|
cfq_put_async_queues(cfqd);
|
|
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
cfq_shutdown_timer_wq(cfqd);
|
|
|
|
kfree(cfqd);
|
|
}
|
|
|
|
static void *cfq_init_queue(struct request_queue *q)
|
|
{
|
|
struct cfq_data *cfqd;
|
|
int i;
|
|
|
|
cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
|
|
if (!cfqd)
|
|
return NULL;
|
|
|
|
cfqd->service_tree = CFQ_RB_ROOT;
|
|
|
|
/*
|
|
* Not strictly needed (since RB_ROOT just clears the node and we
|
|
* zeroed cfqd on alloc), but better be safe in case someone decides
|
|
* to add magic to the rb code
|
|
*/
|
|
for (i = 0; i < CFQ_PRIO_LISTS; i++)
|
|
cfqd->prio_trees[i] = RB_ROOT;
|
|
|
|
INIT_LIST_HEAD(&cfqd->cic_list);
|
|
|
|
cfqd->queue = q;
|
|
|
|
init_timer(&cfqd->idle_slice_timer);
|
|
cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
|
|
cfqd->idle_slice_timer.data = (unsigned long) cfqd;
|
|
|
|
INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
|
|
|
|
cfqd->cfq_quantum = cfq_quantum;
|
|
cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
|
|
cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
|
|
cfqd->cfq_back_max = cfq_back_max;
|
|
cfqd->cfq_back_penalty = cfq_back_penalty;
|
|
cfqd->cfq_slice[0] = cfq_slice_async;
|
|
cfqd->cfq_slice[1] = cfq_slice_sync;
|
|
cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
|
|
cfqd->cfq_slice_idle = cfq_slice_idle;
|
|
cfqd->hw_tag = 1;
|
|
|
|
return cfqd;
|
|
}
|
|
|
|
static void cfq_slab_kill(void)
|
|
{
|
|
/*
|
|
* Caller already ensured that pending RCU callbacks are completed,
|
|
* so we should have no busy allocations at this point.
|
|
*/
|
|
if (cfq_pool)
|
|
kmem_cache_destroy(cfq_pool);
|
|
if (cfq_ioc_pool)
|
|
kmem_cache_destroy(cfq_ioc_pool);
|
|
}
|
|
|
|
static int __init cfq_slab_setup(void)
|
|
{
|
|
cfq_pool = KMEM_CACHE(cfq_queue, 0);
|
|
if (!cfq_pool)
|
|
goto fail;
|
|
|
|
cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
|
|
if (!cfq_ioc_pool)
|
|
goto fail;
|
|
|
|
return 0;
|
|
fail:
|
|
cfq_slab_kill();
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/*
|
|
* sysfs parts below -->
|
|
*/
|
|
static ssize_t
|
|
cfq_var_show(unsigned int var, char *page)
|
|
{
|
|
return sprintf(page, "%d\n", var);
|
|
}
|
|
|
|
static ssize_t
|
|
cfq_var_store(unsigned int *var, const char *page, size_t count)
|
|
{
|
|
char *p = (char *) page;
|
|
|
|
*var = simple_strtoul(p, &p, 10);
|
|
return count;
|
|
}
|
|
|
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#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
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static ssize_t __FUNC(struct elevator_queue *e, char *page) \
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{ \
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struct cfq_data *cfqd = e->elevator_data; \
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unsigned int __data = __VAR; \
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if (__CONV) \
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__data = jiffies_to_msecs(__data); \
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return cfq_var_show(__data, (page)); \
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}
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SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
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SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
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SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
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SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
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SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
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SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
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SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
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SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
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SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
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#undef SHOW_FUNCTION
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#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
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static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
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{ \
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struct cfq_data *cfqd = e->elevator_data; \
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unsigned int __data; \
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int ret = cfq_var_store(&__data, (page), count); \
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if (__data < (MIN)) \
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__data = (MIN); \
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else if (__data > (MAX)) \
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__data = (MAX); \
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if (__CONV) \
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*(__PTR) = msecs_to_jiffies(__data); \
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else \
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*(__PTR) = __data; \
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return ret; \
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}
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STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
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STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
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UINT_MAX, 1);
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STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
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UINT_MAX, 1);
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STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
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STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
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UINT_MAX, 0);
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STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
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STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
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STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
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STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
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UINT_MAX, 0);
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#undef STORE_FUNCTION
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#define CFQ_ATTR(name) \
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__ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
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static struct elv_fs_entry cfq_attrs[] = {
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CFQ_ATTR(quantum),
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CFQ_ATTR(fifo_expire_sync),
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CFQ_ATTR(fifo_expire_async),
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CFQ_ATTR(back_seek_max),
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CFQ_ATTR(back_seek_penalty),
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CFQ_ATTR(slice_sync),
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CFQ_ATTR(slice_async),
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CFQ_ATTR(slice_async_rq),
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CFQ_ATTR(slice_idle),
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__ATTR_NULL
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};
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static struct elevator_type iosched_cfq = {
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.ops = {
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.elevator_merge_fn = cfq_merge,
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.elevator_merged_fn = cfq_merged_request,
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.elevator_merge_req_fn = cfq_merged_requests,
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.elevator_allow_merge_fn = cfq_allow_merge,
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.elevator_dispatch_fn = cfq_dispatch_requests,
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.elevator_add_req_fn = cfq_insert_request,
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.elevator_activate_req_fn = cfq_activate_request,
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.elevator_deactivate_req_fn = cfq_deactivate_request,
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.elevator_queue_empty_fn = cfq_queue_empty,
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.elevator_completed_req_fn = cfq_completed_request,
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.elevator_former_req_fn = elv_rb_former_request,
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.elevator_latter_req_fn = elv_rb_latter_request,
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.elevator_set_req_fn = cfq_set_request,
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.elevator_put_req_fn = cfq_put_request,
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.elevator_may_queue_fn = cfq_may_queue,
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.elevator_init_fn = cfq_init_queue,
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.elevator_exit_fn = cfq_exit_queue,
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.trim = cfq_free_io_context,
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},
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.elevator_attrs = cfq_attrs,
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.elevator_name = "cfq",
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.elevator_owner = THIS_MODULE,
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};
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static int __init cfq_init(void)
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{
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/*
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* could be 0 on HZ < 1000 setups
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*/
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if (!cfq_slice_async)
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cfq_slice_async = 1;
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if (!cfq_slice_idle)
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cfq_slice_idle = 1;
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if (cfq_slab_setup())
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return -ENOMEM;
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elv_register(&iosched_cfq);
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return 0;
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}
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static void __exit cfq_exit(void)
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{
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DECLARE_COMPLETION_ONSTACK(all_gone);
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elv_unregister(&iosched_cfq);
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ioc_gone = &all_gone;
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|
/* ioc_gone's update must be visible before reading ioc_count */
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smp_wmb();
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/*
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|
* this also protects us from entering cfq_slab_kill() with
|
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* pending RCU callbacks
|
|
*/
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if (elv_ioc_count_read(ioc_count))
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wait_for_completion(&all_gone);
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cfq_slab_kill();
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}
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module_init(cfq_init);
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module_exit(cfq_exit);
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MODULE_AUTHOR("Jens Axboe");
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");
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