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9ada9da957
Since zram has no control feature to limit memory usage, it makes hard to manage system memrory. This patch adds new knob "mem_limit" via sysfs to set up the a limit so that zram could fail allocation once it reaches the limit. In addition, user could change the limit in runtime so that he could manage the memory more dynamically. Initial state is no limit so it doesn't break old behavior. [akpm@linux-foundation.org: fix typo, per Sergey] Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: <juno.choi@lge.com> Cc: <seungho1.park@lge.com> Cc: Luigi Semenzato <semenzato@google.com> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Seth Jennings <sjennings@variantweb.net> Cc: David Horner <ds2horner@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
123 lines
3.2 KiB
C
123 lines
3.2 KiB
C
/*
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* Compressed RAM block device
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*
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* Copyright (C) 2008, 2009, 2010 Nitin Gupta
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* 2012, 2013 Minchan Kim
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*
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* This code is released using a dual license strategy: BSD/GPL
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* You can choose the licence that better fits your requirements.
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*
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* Released under the terms of 3-clause BSD License
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* Released under the terms of GNU General Public License Version 2.0
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*
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*/
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#ifndef _ZRAM_DRV_H_
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#define _ZRAM_DRV_H_
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#include <linux/spinlock.h>
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#include <linux/zsmalloc.h>
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#include "zcomp.h"
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/*
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* Some arbitrary value. This is just to catch
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* invalid value for num_devices module parameter.
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*/
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static const unsigned max_num_devices = 32;
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/*-- Configurable parameters */
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/*
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* Pages that compress to size greater than this are stored
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* uncompressed in memory.
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*/
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static const size_t max_zpage_size = PAGE_SIZE / 4 * 3;
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/*
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* NOTE: max_zpage_size must be less than or equal to:
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* ZS_MAX_ALLOC_SIZE. Otherwise, zs_malloc() would
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* always return failure.
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*/
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/*-- End of configurable params */
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#define SECTOR_SHIFT 9
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#define SECTORS_PER_PAGE_SHIFT (PAGE_SHIFT - SECTOR_SHIFT)
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#define SECTORS_PER_PAGE (1 << SECTORS_PER_PAGE_SHIFT)
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#define ZRAM_LOGICAL_BLOCK_SHIFT 12
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#define ZRAM_LOGICAL_BLOCK_SIZE (1 << ZRAM_LOGICAL_BLOCK_SHIFT)
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#define ZRAM_SECTOR_PER_LOGICAL_BLOCK \
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(1 << (ZRAM_LOGICAL_BLOCK_SHIFT - SECTOR_SHIFT))
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/*
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* The lower ZRAM_FLAG_SHIFT bits of table.value is for
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* object size (excluding header), the higher bits is for
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* zram_pageflags.
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*
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* zram is mainly used for memory efficiency so we want to keep memory
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* footprint small so we can squeeze size and flags into a field.
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* The lower ZRAM_FLAG_SHIFT bits is for object size (excluding header),
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* the higher bits is for zram_pageflags.
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*/
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#define ZRAM_FLAG_SHIFT 24
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/* Flags for zram pages (table[page_no].value) */
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enum zram_pageflags {
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/* Page consists entirely of zeros */
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ZRAM_ZERO = ZRAM_FLAG_SHIFT + 1,
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ZRAM_ACCESS, /* page in now accessed */
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__NR_ZRAM_PAGEFLAGS,
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};
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/*-- Data structures */
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/* Allocated for each disk page */
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struct zram_table_entry {
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unsigned long handle;
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unsigned long value;
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};
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struct zram_stats {
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atomic64_t compr_data_size; /* compressed size of pages stored */
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atomic64_t num_reads; /* failed + successful */
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atomic64_t num_writes; /* --do-- */
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atomic64_t failed_reads; /* can happen when memory is too low */
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atomic64_t failed_writes; /* can happen when memory is too low */
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atomic64_t invalid_io; /* non-page-aligned I/O requests */
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atomic64_t notify_free; /* no. of swap slot free notifications */
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atomic64_t zero_pages; /* no. of zero filled pages */
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atomic64_t pages_stored; /* no. of pages currently stored */
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};
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struct zram_meta {
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struct zram_table_entry *table;
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struct zs_pool *mem_pool;
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};
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struct zram {
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struct zram_meta *meta;
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struct request_queue *queue;
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struct gendisk *disk;
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struct zcomp *comp;
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/* Prevent concurrent execution of device init, reset and R/W request */
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struct rw_semaphore init_lock;
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/*
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* This is the limit on amount of *uncompressed* worth of data
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* we can store in a disk.
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*/
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u64 disksize; /* bytes */
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int max_comp_streams;
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struct zram_stats stats;
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/*
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* the number of pages zram can consume for storing compressed data
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*/
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unsigned long limit_pages;
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char compressor[10];
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};
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#endif
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