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15df03c879
For a custom microbenchmark on a 3.30GHz Xeon SandyBridge, which calls
IPC_STAT over and over, it was calculated that, on avg the cost of
ipc_get_maxid() for increasing amounts of keys was:
10 keys: ~900 cycles
100 keys: ~15000 cycles
1000 keys: ~150000 cycles
10000 keys: ~2100000 cycles
This is unsurprising as maxid is currently O(n).
By having the max_id available in O(1) we save all those cycles for each
semctl(_STAT) command, the idr_find can be expensive -- which some real
(customer) workloads actually poll on.
Note that this used to be the case, until commit 7ca7e564e0 ("ipc:
store ipcs into IDRs"). The cost is the extra idr_find when doing
RMIDs, but we simply go backwards, and should not take too many
iterations to find the new value.
[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20170831172049.14576-5-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
168 lines
4.5 KiB
C
168 lines
4.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __IPC_NAMESPACE_H__
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#define __IPC_NAMESPACE_H__
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#include <linux/err.h>
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#include <linux/idr.h>
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#include <linux/rwsem.h>
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#include <linux/notifier.h>
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#include <linux/nsproxy.h>
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#include <linux/ns_common.h>
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#include <linux/refcount.h>
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#include <linux/rhashtable.h>
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struct user_namespace;
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struct ipc_ids {
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int in_use;
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unsigned short seq;
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bool tables_initialized;
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struct rw_semaphore rwsem;
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struct idr ipcs_idr;
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int max_id;
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#ifdef CONFIG_CHECKPOINT_RESTORE
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int next_id;
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#endif
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struct rhashtable key_ht;
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};
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struct ipc_namespace {
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refcount_t count;
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struct ipc_ids ids[3];
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int sem_ctls[4];
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int used_sems;
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unsigned int msg_ctlmax;
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unsigned int msg_ctlmnb;
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unsigned int msg_ctlmni;
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atomic_t msg_bytes;
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atomic_t msg_hdrs;
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size_t shm_ctlmax;
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size_t shm_ctlall;
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unsigned long shm_tot;
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int shm_ctlmni;
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/*
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* Defines whether IPC_RMID is forced for _all_ shm segments regardless
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* of shmctl()
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*/
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int shm_rmid_forced;
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struct notifier_block ipcns_nb;
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/* The kern_mount of the mqueuefs sb. We take a ref on it */
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struct vfsmount *mq_mnt;
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/* # queues in this ns, protected by mq_lock */
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unsigned int mq_queues_count;
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/* next fields are set through sysctl */
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unsigned int mq_queues_max; /* initialized to DFLT_QUEUESMAX */
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unsigned int mq_msg_max; /* initialized to DFLT_MSGMAX */
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unsigned int mq_msgsize_max; /* initialized to DFLT_MSGSIZEMAX */
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unsigned int mq_msg_default;
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unsigned int mq_msgsize_default;
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/* user_ns which owns the ipc ns */
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struct user_namespace *user_ns;
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struct ucounts *ucounts;
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struct ns_common ns;
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} __randomize_layout;
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extern struct ipc_namespace init_ipc_ns;
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extern spinlock_t mq_lock;
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#ifdef CONFIG_SYSVIPC
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extern void shm_destroy_orphaned(struct ipc_namespace *ns);
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#else /* CONFIG_SYSVIPC */
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static inline void shm_destroy_orphaned(struct ipc_namespace *ns) {}
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#endif /* CONFIG_SYSVIPC */
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#ifdef CONFIG_POSIX_MQUEUE
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extern int mq_init_ns(struct ipc_namespace *ns);
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/*
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* POSIX Message Queue default values:
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*
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* MIN_*: Lowest value an admin can set the maximum unprivileged limit to
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* DFLT_*MAX: Default values for the maximum unprivileged limits
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* DFLT_{MSG,MSGSIZE}: Default values used when the user doesn't supply
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* an attribute to the open call and the queue must be created
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* HARD_*: Highest value the maximums can be set to. These are enforced
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* on CAP_SYS_RESOURCE apps as well making them inviolate (so make them
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* suitably high)
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*
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* POSIX Requirements:
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* Per app minimum openable message queues - 8. This does not map well
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* to the fact that we limit the number of queues on a per namespace
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* basis instead of a per app basis. So, make the default high enough
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* that no given app should have a hard time opening 8 queues.
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* Minimum maximum for HARD_MSGMAX - 32767. I bumped this to 65536.
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* Minimum maximum for HARD_MSGSIZEMAX - POSIX is silent on this. However,
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* we have run into a situation where running applications in the wild
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* require this to be at least 5MB, and preferably 10MB, so I set the
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* value to 16MB in hopes that this user is the worst of the bunch and
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* the new maximum will handle anyone else. I may have to revisit this
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* in the future.
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*/
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#define DFLT_QUEUESMAX 256
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#define MIN_MSGMAX 1
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#define DFLT_MSG 10U
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#define DFLT_MSGMAX 10
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#define HARD_MSGMAX 65536
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#define MIN_MSGSIZEMAX 128
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#define DFLT_MSGSIZE 8192U
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#define DFLT_MSGSIZEMAX 8192
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#define HARD_MSGSIZEMAX (16*1024*1024)
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#else
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static inline int mq_init_ns(struct ipc_namespace *ns) { return 0; }
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#endif
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#if defined(CONFIG_IPC_NS)
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extern struct ipc_namespace *copy_ipcs(unsigned long flags,
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struct user_namespace *user_ns, struct ipc_namespace *ns);
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static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
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{
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if (ns)
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refcount_inc(&ns->count);
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return ns;
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}
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extern void put_ipc_ns(struct ipc_namespace *ns);
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#else
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static inline struct ipc_namespace *copy_ipcs(unsigned long flags,
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struct user_namespace *user_ns, struct ipc_namespace *ns)
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{
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if (flags & CLONE_NEWIPC)
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return ERR_PTR(-EINVAL);
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return ns;
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}
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static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
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{
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return ns;
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}
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static inline void put_ipc_ns(struct ipc_namespace *ns)
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{
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}
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#endif
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#ifdef CONFIG_POSIX_MQUEUE_SYSCTL
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struct ctl_table_header;
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extern struct ctl_table_header *mq_register_sysctl_table(void);
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#else /* CONFIG_POSIX_MQUEUE_SYSCTL */
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static inline struct ctl_table_header *mq_register_sysctl_table(void)
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{
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return NULL;
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}
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#endif /* CONFIG_POSIX_MQUEUE_SYSCTL */
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#endif
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