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f2fs: add a sysfs entry to control max_victim_search 

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>
This commit is contained in:
Jaegeuk Kim 2014-01-08 13:45:08 +09:00
parent fb5566da91
commit b1c57c1caa
4 changed files with 12 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
fs/f2fs/f2fs.h
View File

@ -451,6 +451,9 @@ struct f2fs_sb_info {
struct f2fs_gc_kthread *gc_thread; /* GC thread */
unsigned int cur_victim_sec; /* current victim section num */
/* maximum # of trials to find a victim segment for SSR and GC */
unsigned int max_victim_search;
/*
* for stat information.
* one is for the LFS mode, and the other is for the SSR mode.

4
fs/f2fs/gc.c
View File

@ -163,8 +163,8 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
p->ofs_unit = sbi->segs_per_sec;
}
if (p->max_search > MAX_VICTIM_SEARCH)
p->max_search = MAX_VICTIM_SEARCH;
if (p->max_search > sbi->max_victim_search)
p->max_search = sbi->max_victim_search;
p->offset = sbi->last_victim[p->gc_mode];
}

2
fs/f2fs/gc.h
View File

@ -20,7 +20,7 @@
#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 4096 /* covers 8GB */
#define DEF_MAX_VICTIM_SEARCH 4096 /* covers 8GB */
struct f2fs_gc_kthread {
struct task_struct *f2fs_gc_task;

6
fs/f2fs/super.c
View File

@ -74,6 +74,7 @@ static match_table_t f2fs_tokens = {
enum {
GC_THREAD, /* struct f2fs_gc_thread */
SM_INFO, /* struct f2fs_sm_info */
F2FS_SBI, /* struct f2fs_sb_info */
};
struct f2fs_attr {
@ -91,6 +92,8 @@ static unsigned char *__struct_ptr(struct f2fs_sb_info *sbi, int struct_type)
return (unsigned char *)sbi->gc_thread;
else if (struct_type == SM_INFO)
return (unsigned char *)SM_I(sbi);
else if (struct_type == F2FS_SBI)
return (unsigned char *)sbi;
return NULL;
}
@ -180,6 +183,7 @@ F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, reclaim_segments, rec_prefree_segments);
F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, max_small_discards, max_discards);
F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, ipu_policy, ipu_policy);
F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, min_ipu_util, min_ipu_util);
F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, max_victim_search, max_victim_search);
#define ATTR_LIST(name) (&f2fs_attr_##name.attr)
static struct attribute *f2fs_attrs[] = {
@ -191,6 +195,7 @@ static struct attribute *f2fs_attrs[] = {
ATTR_LIST(max_small_discards),
ATTR_LIST(ipu_policy),
ATTR_LIST(min_ipu_util),
ATTR_LIST(max_victim_search),
NULL,
};
@ -775,6 +780,7 @@ static void init_sb_info(struct f2fs_sb_info *sbi)
sbi->node_ino_num = le32_to_cpu(raw_super->node_ino);
sbi->meta_ino_num = le32_to_cpu(raw_super->meta_ino);
sbi->cur_victim_sec = NULL_SECNO;
sbi->max_victim_search = DEF_MAX_VICTIM_SEARCH;
for (i = 0; i < NR_COUNT_TYPE; i++)
atomic_set(&sbi->nr_pages[i], 0);