In our production environment, we find that mounting a 500M and
clean /boot needs ~6 seconds sometimes. The one cause is that
xlog_write_log_records() uses ffs 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. As xlog_write_log_records() has handled bigger
buffer very well, we can use roundup_pow_of_two instead of ffs to
decide buffer size.
Signed-off-by: Wang Jianchao <jianchwa@xxxxxxxxxxx>
---
fs/xfs/xfs_log_recover.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 82c81d20459d..9368fefe1d0a 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -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
