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From: Dave Chinner <david@fromorbit.com>
To: linux-xfs@vger.kernel.org
Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org
Subject: [PATCH 08/26] mm: directed shrinker work deferral
Date: Wed,  9 Oct 2019 14:21:06 +1100
Message-ID: <20191009032124.10541-9-david@fromorbit.com> (raw)
In-Reply-To: <20191009032124.10541-1-david@fromorbit.com>

From: Dave Chinner <dchinner@redhat.com>

Introduce a mechanism for ->count_objects() to indicate to the
shrinker infrastructure that the reclaim context will not allow
scanning work to be done and so the work it decides is necessary
needs to be deferred.

This simplifies the code by separating out the accounting of
deferred work from the actual doing of the work, and allows better
decisions to be made by the shrinekr control logic on what action it
can take.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 include/linux/shrinker.h | 7 +++++++
 mm/vmscan.c              | 8 ++++++++
 2 files changed, 15 insertions(+)

diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
index 0f80123650e2..3405c39ab92c 100644
--- a/include/linux/shrinker.h
+++ b/include/linux/shrinker.h
@@ -31,6 +31,13 @@ struct shrink_control {
 
 	/* current memcg being shrunk (for memcg aware shrinkers) */
 	struct mem_cgroup *memcg;
+
+	/*
+	 * set by ->count_objects if reclaim context prevents reclaim from
+	 * occurring. This allows the shrinker to immediately defer all the
+	 * work and not even attempt to scan the cache.
+	 */
+	bool defer_work;
 };
 
 #define SHRINK_STOP (~0UL)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index c6659bb758a4..1445bc7578c0 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -535,6 +535,13 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
 	trace_mm_shrink_slab_start(shrinker, shrinkctl, nr,
 				   freeable, delta, total_scan, priority);
 
+	/*
+	 * If the shrinker can't run (e.g. due to gfp_mask constraints), then
+	 * defer the work to a context that can scan the cache.
+	 */
+	if (shrinkctl->defer_work)
+		goto done;
+
 	/*
 	 * Normally, we should not scan less than batch_size objects in one
 	 * pass to avoid too frequent shrinker calls, but if the slab has less
@@ -569,6 +576,7 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
 		cond_resched();
 	}
 
+done:
 	if (next_deferred >= scanned)
 		next_deferred -= scanned;
 	else
-- 
2.23.0.rc1



  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 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
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 ` Dave Chinner [this message]
2019-10-14  8:46   ` [PATCH 08/26] mm: directed shrinker work deferral 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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