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b1c57c1caa
Previously during SSR and GC, the maximum number of retrials to find a victim
segment was hard-coded by MAX_VICTIM_SEARCH, 4096 by default.
This number makes an effect on IO locality, when SSR mode is activated, which
results in performance fluctuation on some low-end devices.
If max_victim_search = 4, the victim will be searched like below.
("D" represents a dirty segment, and "*" indicates a selected victim segment.)
D1 D2 D3 D4 D5 D6 D7 D8 D9
[ * ]
[ * ]
[ * ]
[ ....]
This patch adds a sysfs entry to control the number dynamically through:
/sys/fs/f2fs/$dev/max_victim_search
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
111 lines
3.0 KiB
C
111 lines
3.0 KiB
C
/*
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* fs/f2fs/gc.h
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*
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* Copyright (c) 2012 Samsung Electronics Co., Ltd.
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* http://www.samsung.com/
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#define GC_THREAD_MIN_WB_PAGES 1 /*
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* a threshold to determine
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* whether IO subsystem is idle
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* or not
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*/
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#define DEF_GC_THREAD_MIN_SLEEP_TIME 30000 /* milliseconds */
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#define DEF_GC_THREAD_MAX_SLEEP_TIME 60000
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#define DEF_GC_THREAD_NOGC_SLEEP_TIME 300000 /* wait 5 min */
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#define LIMIT_INVALID_BLOCK 40 /* percentage over total user space */
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#define LIMIT_FREE_BLOCK 40 /* percentage over invalid + free space */
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/* Search max. number of dirty segments to select a victim segment */
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#define DEF_MAX_VICTIM_SEARCH 4096 /* covers 8GB */
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struct f2fs_gc_kthread {
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struct task_struct *f2fs_gc_task;
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wait_queue_head_t gc_wait_queue_head;
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/* for gc sleep time */
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unsigned int min_sleep_time;
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unsigned int max_sleep_time;
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unsigned int no_gc_sleep_time;
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/* for changing gc mode */
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unsigned int gc_idle;
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};
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struct inode_entry {
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struct list_head list;
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struct inode *inode;
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};
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/*
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* inline functions
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*/
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static inline block_t free_user_blocks(struct f2fs_sb_info *sbi)
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{
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if (free_segments(sbi) < overprovision_segments(sbi))
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return 0;
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else
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return (free_segments(sbi) - overprovision_segments(sbi))
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<< sbi->log_blocks_per_seg;
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}
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static inline block_t limit_invalid_user_blocks(struct f2fs_sb_info *sbi)
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{
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return (long)(sbi->user_block_count * LIMIT_INVALID_BLOCK) / 100;
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}
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static inline block_t limit_free_user_blocks(struct f2fs_sb_info *sbi)
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{
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block_t reclaimable_user_blocks = sbi->user_block_count -
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written_block_count(sbi);
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return (long)(reclaimable_user_blocks * LIMIT_FREE_BLOCK) / 100;
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}
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static inline long increase_sleep_time(struct f2fs_gc_kthread *gc_th, long wait)
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{
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if (wait == gc_th->no_gc_sleep_time)
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return wait;
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wait += gc_th->min_sleep_time;
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if (wait > gc_th->max_sleep_time)
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wait = gc_th->max_sleep_time;
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return wait;
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}
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static inline long decrease_sleep_time(struct f2fs_gc_kthread *gc_th, long wait)
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{
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if (wait == gc_th->no_gc_sleep_time)
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wait = gc_th->max_sleep_time;
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wait -= gc_th->min_sleep_time;
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if (wait <= gc_th->min_sleep_time)
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wait = gc_th->min_sleep_time;
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return wait;
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}
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static inline bool has_enough_invalid_blocks(struct f2fs_sb_info *sbi)
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{
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block_t invalid_user_blocks = sbi->user_block_count -
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written_block_count(sbi);
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/*
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* Background GC is triggered with the following condition.
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* 1. There are a number of invalid blocks.
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* 2. There is not enough free space.
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*/
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if (invalid_user_blocks > limit_invalid_user_blocks(sbi) &&
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free_user_blocks(sbi) < limit_free_user_blocks(sbi))
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return true;
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return false;
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}
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static inline int is_idle(struct f2fs_sb_info *sbi)
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{
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struct block_device *bdev = sbi->sb->s_bdev;
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struct request_queue *q = bdev_get_queue(bdev);
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struct request_list *rl = &q->root_rl;
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return !(rl->count[BLK_RW_SYNC]) && !(rl->count[BLK_RW_ASYNC]);
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}
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