From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-xfs@vger.kernel.org, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 03/26] xfs: don't allow log IO to be throttled
Date: Wed, 30 Oct 2019 10:14:22 -0700 [thread overview]
Message-ID: <20191030171422.GM15222@magnolia> (raw)
In-Reply-To: <20191009032124.10541-4-david@fromorbit.com>
On Wed, Oct 09, 2019 at 02:21:01PM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> Running metadata intensive workloads, I've been seeing the AIL
> pushing getting stuck on pinned buffers and triggering log forces.
> The log force is taking a long time to run because the log IO is
> getting throttled by wbt_wait() - the block layer writeback
> throttle. It's being throttled because there is a huge amount of
> metadata writeback going on which is filling the request queue.
>
> IOWs, we have a priority inversion problem here.
>
> Mark the log IO bios with REQ_IDLE so they don't get throttled
> by the block layer writeback throttle. When we are forcing the CIL,
> we are likely to need to to tens of log IOs, and they are issued as
> fast as they can be build and IO completed. Hence REQ_IDLE is
> appropriate - it's an indication that more IO will follow shortly.
>
> And because we also set REQ_SYNC, the writeback throttle will no
> treat log IO the same way it treats direct IO writes - it will not
> throttle them at all. Hence we solve the priority inversion problem
> caused by the writeback throttle being unable to distinguish between
> high priority log IO and background metadata writeback.
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
--D
> ---
> fs/xfs/xfs_log.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
> index 6f99d6eae6a4..cf098e19967e 100644
> --- a/fs/xfs/xfs_log.c
> +++ b/fs/xfs/xfs_log.c
> @@ -1751,7 +1751,15 @@ xlog_write_iclog(
> iclog->ic_bio.bi_iter.bi_sector = log->l_logBBstart + bno;
> iclog->ic_bio.bi_end_io = xlog_bio_end_io;
> iclog->ic_bio.bi_private = iclog;
> - iclog->ic_bio.bi_opf = REQ_OP_WRITE | REQ_META | REQ_SYNC | REQ_FUA;
> +
> + /*
> + * We use REQ_SYNC | REQ_IDLE here to tell the block layer the are more
> + * IOs coming immediately after this one. This prevents the block layer
> + * writeback throttle from throttling log writes behind background
> + * metadata writeback and causing priority inversions.
> + */
> + iclog->ic_bio.bi_opf = REQ_OP_WRITE | REQ_META | REQ_SYNC |
> + REQ_IDLE | REQ_FUA;
> if (need_flush)
> iclog->ic_bio.bi_opf |= REQ_PREFLUSH;
>
> --
> 2.23.0.rc1
>
next prev parent reply other threads:[~2019-10-30 17:14 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-09 3:20 [PATCH V2 00/26] mm, xfs: non-blocking inode reclaim Dave Chinner
2019-10-09 3:20 ` [PATCH 01/26] xfs: Lower CIL flush limit for large logs Dave Chinner
2019-10-11 12:39 ` Brian Foster
2019-10-30 17:08 ` Darrick J. Wong
2019-10-09 3:21 ` [PATCH 02/26] xfs: Throttle commits on delayed background CIL push Dave Chinner
2019-10-11 12:38 ` Brian Foster
2019-10-09 3:21 ` [PATCH 03/26] xfs: don't allow log IO to be throttled Dave Chinner
2019-10-11 9:35 ` Christoph Hellwig
2019-10-11 12:39 ` Brian Foster
2019-10-30 17:14 ` Darrick J. Wong [this message]
2019-10-09 3:21 ` [PATCH 04/26] xfs: Improve metadata buffer reclaim accountability Dave Chinner
2019-10-11 12:39 ` Brian Foster
2019-10-11 12:57 ` Christoph Hellwig
2019-10-11 23:14 ` Dave Chinner
2019-10-11 23:13 ` Dave Chinner
2019-10-12 12:05 ` Brian Foster
2019-10-13 3:14 ` Dave Chinner
2019-10-14 13:05 ` Brian Foster
2019-10-30 17:25 ` Darrick J. Wong
2019-10-30 21:43 ` Dave Chinner
2019-10-31 3:06 ` Darrick J. Wong
2019-10-31 20:50 ` Dave Chinner
2019-10-31 21:05 ` Darrick J. Wong
2019-10-31 21:22 ` Christoph Hellwig
2019-11-03 21:26 ` Dave Chinner
2019-11-04 23:08 ` Darrick J. Wong
2019-10-09 3:21 ` [PATCH 05/26] xfs: correctly acount for reclaimable slabs Dave Chinner
2019-10-11 12:39 ` Brian Foster
2019-10-30 17:16 ` Darrick J. Wong
2019-10-09 3:21 ` [PATCH 06/26] xfs: synchronous AIL pushing Dave Chinner
2019-10-11 9:42 ` Christoph Hellwig
2019-10-11 12:40 ` Brian Foster
2019-10-11 23:15 ` Dave Chinner
2019-10-09 3:21 ` [PATCH 07/26] xfs: tail updates only need to occur when LSN changes Dave Chinner
2019-10-11 9:50 ` Christoph Hellwig
2019-10-11 12:40 ` Brian Foster
2019-10-09 3:21 ` [PATCH 08/26] mm: directed shrinker work deferral Dave Chinner
2019-10-14 8:46 ` Christoph Hellwig
2019-10-14 13:06 ` Brian Foster
2019-10-18 7:59 ` Dave Chinner
2019-10-09 3:21 ` [PATCH 09/26] shrinkers: use defer_work for GFP_NOFS sensitive shrinkers Dave Chinner
2019-10-09 3:21 ` [PATCH 10/26] mm: factor shrinker work calculations Dave Chinner
2019-10-09 3:21 ` [PATCH 11/26] shrinker: defer work only to kswapd Dave Chinner
2019-10-09 3:21 ` [PATCH 12/26] shrinker: clean up variable types and tracepoints Dave Chinner
2019-10-09 3:21 ` [PATCH 13/26] mm: reclaim_state records pages reclaimed, not slabs Dave Chinner
2019-10-09 3:21 ` [PATCH 14/26] mm: back off direct reclaim on excessive shrinker deferral Dave Chinner
2019-10-11 16:21 ` Matthew Wilcox
2019-10-11 23:20 ` Dave Chinner
2019-10-09 3:21 ` [PATCH 15/26] mm: kswapd backoff for shrinkers Dave Chinner
2019-10-09 3:21 ` [PATCH 16/26] xfs: synchronous AIL pushing Dave Chinner
2019-10-11 10:18 ` Christoph Hellwig
2019-10-11 15:29 ` Brian Foster
2019-10-11 23:27 ` Dave Chinner
2019-10-12 12:08 ` Brian Foster
2019-10-09 3:21 ` [PATCH 17/26] xfs: don't block kswapd in inode reclaim Dave Chinner
2019-10-11 15:29 ` Brian Foster
2019-10-09 3:21 ` [PATCH 18/26] xfs: reduce kswapd blocking on inode locking Dave Chinner
2019-10-11 10:29 ` Christoph Hellwig
2019-10-09 3:21 ` [PATCH 19/26] xfs: kill background reclaim work Dave Chinner
2019-10-11 10:31 ` Christoph Hellwig
2019-10-09 3:21 ` [PATCH 20/26] xfs: use AIL pushing for inode reclaim IO Dave Chinner
2019-10-11 17:38 ` Brian Foster
2019-10-09 3:21 ` [PATCH 21/26] xfs: remove mode from xfs_reclaim_inodes() Dave Chinner
2019-10-11 10:39 ` Christoph Hellwig
2019-10-14 13:07 ` Brian Foster
2019-10-09 3:21 ` [PATCH 22/26] xfs: track reclaimable inodes using a LRU list Dave Chinner
2019-10-11 10:42 ` Christoph Hellwig
2019-10-14 13:07 ` Brian Foster
2019-10-09 3:21 ` [PATCH 23/26] xfs: reclaim inodes from the LRU Dave Chinner
2019-10-11 10:56 ` Christoph Hellwig
2019-10-30 23:25 ` Dave Chinner
2019-10-09 3:21 ` [PATCH 24/26] xfs: remove unusued old inode reclaim code Dave Chinner
2019-10-09 3:21 ` [PATCH 25/26] xfs: rework unreferenced inode lookups Dave Chinner
2019-10-11 12:55 ` Christoph Hellwig
2019-10-11 13:39 ` Peter Zijlstra
2019-10-11 23:38 ` Dave Chinner
2019-10-14 13:07 ` Brian Foster
2019-10-17 1:24 ` Dave Chinner
2019-10-17 7:57 ` Brian Foster
2019-10-18 20:29 ` Dave Chinner
2019-10-09 3:21 ` [PATCH 26/26] xfs: use xfs_ail_push_all_sync in xfs_reclaim_inodes Dave Chinner
2019-10-11 9:55 ` Christoph Hellwig
2019-10-09 7:06 ` [PATCH V2 00/26] mm, xfs: non-blocking inode reclaim Christoph Hellwig
2019-10-11 19:03 ` Josef Bacik
2019-10-11 23:48 ` Dave Chinner
2019-10-12 0:19 ` Josef Bacik
2019-10-12 0:48 ` Dave Chinner
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