From: Brian Foster <bfoster@redhat.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 17/26] xfs: don't block kswapd in inode reclaim Date: Fri, 11 Oct 2019 11:29:57 -0400 Message-ID: <20191011152957.GI61257@bfoster> (raw) In-Reply-To: <20191009032124.10541-18-david@fromorbit.com> On Wed, Oct 09, 2019 at 02:21:15PM +1100, Dave Chinner wrote: > From: Dave Chinner <dchinner@redhat.com> > > We have a number of reasons for blocking kswapd in XFS inode > reclaim, mainly all to do with the fact that memory reclaim has no > feedback mechanisms to throttle on dirty slab objects that need IO > to reclaim. > > As a result, we currently throttle inode reclaim by issuing IO in > the reclaim context. The unfortunate side effect of this is that it > can cause long tail latencies in reclaim and for some workloads this > can be a problem. > > Now that the shrinkers finally have a method of telling kswapd to > back off, we can start the process of making inode reclaim in XFS > non-blocking. The first thing we need to do is not block kswapd, but > so that doesn't cause immediate serious problems, make sure inode > writeback is always underway when kswapd is running. > > As we don't block kswapd now, we don't have to worry about reclaim > scans taking long delays due to IO being issued and waited for. > Hence while direct reclaim gets delayed by IO, kswapd will not and > so it will keep pushing the AIL to clean inodes. Hence direct > reclaim doesn't need to push the AIL anymore as kswapd will do it > reliably now. > > Signed-off-by: Dave Chinner <dchinner@redhat.com> > --- Reviewed-by: Brian Foster <bfoster@redhat.com> > fs/xfs/xfs_icache.c | 17 ++++++++++++++--- > 1 file changed, 14 insertions(+), 3 deletions(-) > > diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c > index 944add5ff8e0..edcc3f6bb3bf 100644 > --- a/fs/xfs/xfs_icache.c > +++ b/fs/xfs/xfs_icache.c > @@ -1378,11 +1378,22 @@ xfs_reclaim_inodes_nr( > struct xfs_mount *mp, > int nr_to_scan) > { > - /* kick background reclaimer and push the AIL */ > + int sync_mode = SYNC_TRYLOCK; > + > + /* kick background reclaimer */ > xfs_reclaim_work_queue(mp); > - xfs_ail_push_all(mp->m_ail); > > - return xfs_reclaim_inodes_ag(mp, SYNC_TRYLOCK | SYNC_WAIT, &nr_to_scan); > + /* > + * For kswapd, we kick background inode writeback. For direct > + * reclaim, we issue and wait on inode writeback to throttle > + * reclaim rates and avoid shouty OOM-death. > + */ > + if (current_is_kswapd()) > + xfs_ail_push_all(mp->m_ail); > + else > + sync_mode |= SYNC_WAIT; > + > + return xfs_reclaim_inodes_ag(mp, sync_mode, &nr_to_scan); > } > > /* > -- > 2.23.0.rc1 >
next prev parent reply index 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 " 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 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 [this message] 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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