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| author | Daeho Jeong <daehojeong@google.com> | 2021-09-29 11:12:03 -0700 |
|---|---|---|
| committer | Jaegeuk Kim <jaegeuk@kernel.org> | 2021-10-26 14:04:30 -0700 |
| commit | 6691d940b0e09dd1564130e7a354d6deaf05d009 (patch) | |
| tree | ae609ea58abdfd7ce7c73e72f82d39226f2de3a9 /fs/f2fs/gc.c | |
| parent | 84eab2a899f28137e51a36861ed2df9579f54ebe (diff) | |
| download | lwn-6691d940b0e09dd1564130e7a354d6deaf05d009.tar.gz lwn-6691d940b0e09dd1564130e7a354d6deaf05d009.zip | |
f2fs: introduce fragment allocation mode mount option
Added two options into "mode=" mount option to make it possible for
developers to simulate filesystem fragmentation/after-GC situation
itself. The developers use these modes to understand filesystem
fragmentation/after-GC condition well, and eventually get some
insights to handle them better.
"fragment:segment": f2fs allocates a new segment in ramdom position.
With this, we can simulate the after-GC condition.
"fragment:block" : We can scatter block allocation with
"max_fragment_chunk" and "max_fragment_hole" sysfs
nodes. f2fs will allocate 1..<max_fragment_chunk>
blocks in a chunk and make a hole in the length of
1..<max_fragment_hole> by turns in a newly allocated
free segment. Plus, this mode implicitly enables
"fragment:segment" option for more randomness.
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Daeho Jeong <daehojeong@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Diffstat (limited to 'fs/f2fs/gc.c')
| -rw-r--r-- | fs/f2fs/gc.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c index 77391e3b7d68..a946ce0ead34 100644 --- a/fs/f2fs/gc.c +++ b/fs/f2fs/gc.c @@ -14,6 +14,7 @@ #include <linux/delay.h> #include <linux/freezer.h> #include <linux/sched/signal.h> +#include <linux/random.h> #include "f2fs.h" #include "node.h" @@ -257,7 +258,9 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type, p->max_search = sbi->max_victim_search; /* let's select beginning hot/small space first in no_heap mode*/ - if (test_opt(sbi, NOHEAP) && + if (f2fs_need_rand_seg(sbi)) + p->offset = prandom_u32() % (MAIN_SECS(sbi) * sbi->segs_per_sec); + else if (test_opt(sbi, NOHEAP) && (type == CURSEG_HOT_DATA || IS_NODESEG(type))) p->offset = 0; else |