From 373ac521799d9e97061515aca6ec6621789036bb Mon Sep 17 00:00:00 2001
From: Zhang Yi <yi.zhang@huawei.com>
Date: Fri, 14 Jul 2023 10:55:26 +0800
Subject: [PATCH] jbd2: fix checkpoint cleanup performance regression
Git-commit: 373ac521799d9e97061515aca6ec6621789036bb
Patch-mainline: v6.6-rc1
References: bsc#1214952
journal_clean_one_cp_list() has been merged into
journal_shrink_one_cp_list(), but do chekpoint buffer cleanup from the
committing process is just a best effort, it should stop scan once it
meet a busy buffer, or else it will cause a lot of invalid buffer scan
and checks. We catch a performance regression when doing fs_mark tests
below.
Test cmd:
./fs_mark -d scratch -s 1024 -n 10000 -t 1 -D 100 -N 100
Before merging checkpoint buffer cleanup:
FSUse% Count Size Files/sec App Overhead
95 10000 1024 8304.9 49033
After merging checkpoint buffer cleanup:
FSUse% Count Size Files/sec App Overhead
95 10000 1024 7649.0 50012
FSUse% Count Size Files/sec App Overhead
95 10000 1024 2107.1 50871
After merging checkpoint buffer cleanup, the total loop count in
journal_shrink_one_cp_list() could be up to 6,261,600+ (50,000+ ~
100,000+ in general), most of them are invalid. This patch fix it
through passing 'shrink_type' into journal_shrink_one_cp_list() and add
a new 'SHRINK_BUSY_STOP' to indicate it should stop once meet a busy
buffer. After fix, the loop count descending back to 10,000+.
After this fix:
FSUse% Count Size Files/sec App Overhead
95 10000 1024 8558.4 49109
Cc: stable@kernel.org
Fixes: b98dba273a0e ("jbd2: remove journal_clean_one_cp_list()")
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230714025528.564988-2-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Acked-by: Jan Kara <jack@suse.cz>
---
fs/jbd2/checkpoint.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/jbd2/checkpoint.c
+++ b/fs/jbd2/checkpoint.c
@@ -374,7 +374,7 @@ static int journal_clean_one_cp_list(str
} else {
ret = jbd2_journal_try_remove_checkpoint(jh);
if (ret < 0)
- continue;
+ break;
}
if (ret)
return ret;