2022-06-30 11:44:02

by Guowei Du

Subject: [PATCH 7/7] f2fs: optimize shrink count

From: duguowei <[email protected]>

Remove the local variable 'run_no', add comments for better
reading.

Signed-off-by: duguowei <[email protected]>
---
fs/f2fs/shrinker.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/f2fs/shrinker.c b/fs/f2fs/shrinker.c
index dd3c3c7a90ec..7e439496dfca 100644
--- a/fs/f2fs/shrinker.c
+++ b/fs/f2fs/shrinker.c
@@ -76,18 +76,18 @@ unsigned long f2fs_shrink_scan(struct shrinker *shrink,
unsigned long nr = sc->nr_to_scan;
struct f2fs_sb_info *sbi;
struct list_head *p;
- unsigned int run_no;
unsigned long freed = 0;

spin_lock(&f2fs_list_lock);
- do {
- run_no = ++shrinker_run_no;
- } while (run_no == 0);
+ shrinker_run_no++;
+ /* if overflow, next loop needs to skip number 0 */
+ if (!shrinker_run_no)
+ shrinker_run_no = 1;
p = f2fs_list.next;
while (p != &f2fs_list) {
sbi = list_entry(p, struct f2fs_sb_info, s_list);

- if (sbi->shrinker_run_no == run_no)
+ if (sbi->shrinker_run_no == shrinker_run_no)
break;

/* stop f2fs_put_super */
@@ -97,7 +97,7 @@ unsigned long f2fs_shrink_scan(struct shrinker *shrink,
}
spin_unlock(&f2fs_list_lock);

- sbi->shrinker_run_no = run_no;
+ sbi->shrinker_run_no = shrinker_run_no;

/* shrink extent cache entries */
freed += f2fs_shrink_extent_tree(sbi, nr >> 1);
--
2.36.1

2022-07-01 01:08:10

by Chao Yu

Subject: Re: [PATCH 7/7] f2fs: optimize shrink count

On 2022/6/30 19:26, Guowei Du wrote:
> From: duguowei <[email protected]>
>
> Remove the local variable 'run_no', add comments for better
> reading.

Not sure, I guess original implementation considers the race condition for
f2fs_shrink_scan vs f2fs_shrink_scan case? so it uses a local variable to
keep the per-round context info?

Jaegeuk, please help to check that.

Thanks,

>
> Signed-off-by: duguowei <[email protected]>
> ---
> fs/f2fs/shrinker.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/fs/f2fs/shrinker.c b/fs/f2fs/shrinker.c
> index dd3c3c7a90ec..7e439496dfca 100644
> --- a/fs/f2fs/shrinker.c
> +++ b/fs/f2fs/shrinker.c
> @@ -76,18 +76,18 @@ unsigned long f2fs_shrink_scan(struct shrinker *shrink,
> unsigned long nr = sc->nr_to_scan;
> struct f2fs_sb_info *sbi;
> struct list_head *p;
> - unsigned int run_no;
> unsigned long freed = 0;
>
> spin_lock(&f2fs_list_lock);
> - do {
> - run_no = ++shrinker_run_no;
> - } while (run_no == 0);
> + shrinker_run_no++;
> + /* if overflow, next loop needs to skip number 0 */
> + if (!shrinker_run_no)
> + shrinker_run_no = 1;
> p = f2fs_list.next;
> while (p != &f2fs_list) {
> sbi = list_entry(p, struct f2fs_sb_info, s_list);
>
> - if (sbi->shrinker_run_no == run_no)
> + if (sbi->shrinker_run_no == shrinker_run_no)
> break;
>
> /* stop f2fs_put_super */
> @@ -97,7 +97,7 @@ unsigned long f2fs_shrink_scan(struct shrinker *shrink,
> }
> spin_unlock(&f2fs_list_lock);
>
> - sbi->shrinker_run_no = run_no;
> + sbi->shrinker_run_no = shrinker_run_no;
>
> /* shrink extent cache entries */
> freed += f2fs_shrink_extent_tree(sbi, nr >> 1);