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>
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index b69f190..5f7dc4f 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -451,6 +451,9 @@
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.
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 599f546..9117cca 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -163,8 +163,8 @@
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];
}
diff --git a/fs/f2fs/gc.h b/fs/f2fs/gc.h
index 507056d..5d5eb60 100644
--- a/fs/f2fs/gc.h
+++ b/fs/f2fs/gc.h
@@ -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;
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index f16da92..b070f30 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -74,6 +74,7 @@
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 @@
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, 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 @@
ATTR_LIST(max_small_discards),
ATTR_LIST(ipu_policy),
ATTR_LIST(min_ipu_util),
+ ATTR_LIST(max_victim_search),
NULL,
};
@@ -775,6 +780,7 @@
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);