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Message-ID: <CY8PR05MB9378060FDF6C7E15589EB668CDF1A@CY8PR05MB9378.namprd05.prod.outlook.com>
Date: Tue, 12 Sep 2023 15:20:56 +0800
From: Wang Jianchao <jianchwa@...look.com>
To: djwong@...nel.org
Cc: linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH V2] xfs: use roundup_pow_of_two instead of ffs during
xlog_find_tail
In our production environment, we find that mounting a 500M /boot
which is umount cleanly needs ~6s. One cause is that ffs() is
used by xlog_write_log_records() to decide the buffer size. It
can cause a lot of small IO easily when xlog_clear_stale_blocks()
needs to wrap around the end of log area and log head block is
not power of two. Things are similar in xlog_find_verify_cycle().
The code is able to handed bigger buffer very well, we can use
roundup_pow_of_two() to replace ffs() directly to avoid small
and sychronous IOs.
Changes in V1:
- Also replace the ffs in xlog_find_verify_cycle()
Signed-off-by: Wang Jianchao <wangjc136@...ea.com>
---
fs/xfs/xfs_log_recover.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 82c81d20459d..13b94d2e605b 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -329,7 +329,7 @@ xlog_find_verify_cycle(
* try a smaller size. We need to be able to read at least
* a log sector, or we're out of luck.
*/
- bufblks = 1 << ffs(nbblks);
+ bufblks = roundup_pow_of_two(nbblks);
while (bufblks > log->l_logBBsize)
bufblks >>= 1;
while (!(buffer = xlog_alloc_buffer(log, bufblks))) {
@@ -1528,7 +1528,7 @@ xlog_write_log_records(
* a smaller size. We need to be able to write at least a
* log sector, or we're out of luck.
*/
- bufblks = 1 << ffs(blocks);
+ bufblks = roundup_pow_of_two(blocks);
while (bufblks > log->l_logBBsize)
bufblks >>= 1;
while (!(buffer = xlog_alloc_buffer(log, bufblks))) {
--
2.34.1
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