linux/fs/f2fs/gc.h
Jaegeuk Kim 437275272f f2fs: clarify and enhance the f2fs_gc flow
This patch makes clearer the ambiguous f2fs_gc flow as follows.

1. Remove intermediate checkpoint condition during f2fs_gc
 (i.e., should_do_checkpoint() and GC_BLOCKED)

2. Remove unnecessary return values of f2fs_gc because of #1.
 (i.e., GC_NODE, GC_OK, etc)

3. Simplify write_checkpoint() because of #2.

4. Clarify the main f2fs_gc flow.
 o monitor how many freed sections during one iteration of do_garbage_collect().
 o do GC more without checkpoints if we can't get enough free sections.
 o do checkpoint once we've got enough free sections through forground GCs.

5. Adopt thread-logging (Slack-Space-Recycle) scheme more aggressively on data
  log types. See. get_ssr_segement()

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-02-12 07:15:02 +09:00

97 lines
2.6 KiB
C

/*
* fs/f2fs/gc.h
*
* Copyright (c) 2012 Samsung Electronics Co., Ltd.
* http://www.samsung.com/
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#define GC_THREAD_MIN_WB_PAGES 1 /*
* a threshold to determine
* whether IO subsystem is idle
* or not
*/
#define GC_THREAD_MIN_SLEEP_TIME 10000 /* milliseconds */
#define GC_THREAD_MAX_SLEEP_TIME 30000
#define GC_THREAD_NOGC_SLEEP_TIME 10000
#define LIMIT_INVALID_BLOCK 40 /* percentage over total user space */
#define LIMIT_FREE_BLOCK 40 /* percentage over invalid + free space */
/* Search max. number of dirty segments to select a victim segment */
#define MAX_VICTIM_SEARCH 20
struct f2fs_gc_kthread {
struct task_struct *f2fs_gc_task;
wait_queue_head_t gc_wait_queue_head;
};
struct inode_entry {
struct list_head list;
struct inode *inode;
};
/*
* inline functions
*/
static inline block_t free_user_blocks(struct f2fs_sb_info *sbi)
{
if (free_segments(sbi) < overprovision_segments(sbi))
return 0;
else
return (free_segments(sbi) - overprovision_segments(sbi))
<< sbi->log_blocks_per_seg;
}
static inline block_t limit_invalid_user_blocks(struct f2fs_sb_info *sbi)
{
return (long)(sbi->user_block_count * LIMIT_INVALID_BLOCK) / 100;
}
static inline block_t limit_free_user_blocks(struct f2fs_sb_info *sbi)
{
block_t reclaimable_user_blocks = sbi->user_block_count -
written_block_count(sbi);
return (long)(reclaimable_user_blocks * LIMIT_FREE_BLOCK) / 100;
}
static inline long increase_sleep_time(long wait)
{
wait += GC_THREAD_MIN_SLEEP_TIME;
if (wait > GC_THREAD_MAX_SLEEP_TIME)
wait = GC_THREAD_MAX_SLEEP_TIME;
return wait;
}
static inline long decrease_sleep_time(long wait)
{
wait -= GC_THREAD_MIN_SLEEP_TIME;
if (wait <= GC_THREAD_MIN_SLEEP_TIME)
wait = GC_THREAD_MIN_SLEEP_TIME;
return wait;
}
static inline bool has_enough_invalid_blocks(struct f2fs_sb_info *sbi)
{
block_t invalid_user_blocks = sbi->user_block_count -
written_block_count(sbi);
/*
* Background GC is triggered with the following condition.
* 1. There are a number of invalid blocks.
* 2. There is not enough free space.
*/
if (invalid_user_blocks > limit_invalid_user_blocks(sbi) &&
free_user_blocks(sbi) < limit_free_user_blocks(sbi))
return true;
return false;
}
static inline int is_idle(struct f2fs_sb_info *sbi)
{
struct block_device *bdev = sbi->sb->s_bdev;
struct request_queue *q = bdev_get_queue(bdev);
struct request_list *rl = &q->root_rl;
return !(rl->count[BLK_RW_SYNC]) && !(rl->count[BLK_RW_ASYNC]);
}