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Message-ID: <20230919032138.GC348037@frogsfrogsfrogs>
Date: Mon, 18 Sep 2023 20:21:38 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: Wang Jianchao <jianchwa@...look.com>,
Chandan Babu R <chandanrlinux@...il.com>
Cc: linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3] xfs: use roundup_pow_of_two instead of ffs during
xlog_find_tail
On Tue, Sep 19, 2023 at 10:06:56AM +0800, Wang Jianchao wrote:
> Ping ? Do I need other update on this patch ?
Nope, I think this is ok...
> Thanks
> Jianchao
>
> On 2023/9/13 09:38, Wang Jianchao wrote:
> >
> > 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.
> >
> > Reviewed-by: Dave Chinner <dchinner@...hat.com>
> > Signed-off-by: Wang Jianchao <wangjc136@...ea.com>
...so let's see if the release manager will take this patch.
Chandan? Could you pull in the various one-off patches floating around
on the list that have passed review? ;)
Reviewed-by: Darrick J. Wong <djwong@...nel.org>
PS: If you'd like to send a pull request to push things along, please do
--D
> > ---
> >
> > Changes in V2:
> > - Move change log below "---"
> > - Add reviewed-by Dave Chinner tag
> >
> > Changes in V1:
> > - Also replace the ffs in xlog_find_verify_cycle()
> >
> > 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))) {
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