From: Mel Gorman <mgorman@techsingularity.net>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Linux-MM <linux-mm@kvack.org>, NeilBrown <neilb@suse.de>,
Theodore Ts'o <tytso@mit.edu>,
Andreas Dilger <adilger.kernel@dilger.ca>,
"Darrick J . Wong" <djwong@kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Michal Hocko <mhocko@suse.com>,
Dave Chinner <david@fromorbit.com>,
Rik van Riel <riel@surriel.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Jonathan Corbet <corbet@lwn.net>,
Linux-fsdevel <linux-fsdevel@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/8] mm/vmscan: Throttle reclaim when no progress is being made
Date: Thu, 14 Oct 2021 14:03:12 +0100 [thread overview]
Message-ID: <20211014130312.GA3959@techsingularity.net> (raw)
In-Reply-To: <63336163-e709-65de-6d53-8764facd3924@suse.cz>
On Thu, Oct 14, 2021 at 02:31:17PM +0200, Vlastimil Babka wrote:
> On 10/8/21 15:53, Mel Gorman wrote:
> > Memcg reclaim throttles on congestion if no reclaim progress is made.
> > This makes little sense, it might be due to writeback or a host of
> > other factors.
> >
> > For !memcg reclaim, it's messy. Direct reclaim primarily is throttled
> > in the page allocator if it is failing to make progress. Kswapd
> > throttles if too many pages are under writeback and marked for
> > immediate reclaim.
> >
> > This patch explicitly throttles if reclaim is failing to make progress.
> >
> > Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
> ...
> > @@ -3769,6 +3797,16 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
> > trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed);
> > set_task_reclaim_state(current, NULL);
> >
> > + if (!nr_reclaimed) {
> > + struct zoneref *z;
> > + pg_data_t *pgdat;
> > +
> > + z = first_zones_zonelist(zonelist, sc.reclaim_idx, sc.nodemask);
> > + pgdat = zonelist_zone(z)->zone_pgdat;
> > +
> > + reclaim_throttle(pgdat, VMSCAN_THROTTLE_NOPROGRESS, HZ/10);
> > + }
>
> Is this necessary? AFAICS here we just returned from:
>
> do_try_to_free_pages()
> shrink_zones()
> for_each_zone()...
> consider_reclaim_throttle()
>
> Which already throttles when needed and using the appropriate pgdat, while
> here we have to somewhat awkwardly assume the preferred one.
>
Yes, you're right, consider_reclaim_throttle not only throttles on the
appropriate pgdat but takes priority into account.
Well spotted!
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2021-10-14 13:03 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-08 13:53 [PATCH v3 0/8] Remove dependency on congestion_wait in mm/ Mel Gorman
2021-10-08 13:53 ` [PATCH 1/8] mm/vmscan: Throttle reclaim until some writeback completes if congested Mel Gorman
2021-10-13 15:39 ` Vlastimil Babka
2021-10-14 10:47 ` Mel Gorman
2021-10-14 15:42 ` Vlastimil Babka
2021-10-08 13:53 ` [PATCH 2/8] mm/vmscan: Throttle reclaim and compaction when too may pages are isolated Mel Gorman
2021-10-14 8:06 ` Vlastimil Babka
2021-10-14 11:56 ` Mel Gorman
2021-10-14 15:44 ` Vlastimil Babka
2021-10-08 13:53 ` [PATCH 3/8] mm/vmscan: Throttle reclaim when no progress is being made Mel Gorman
2021-10-14 12:31 ` Vlastimil Babka
2021-10-14 13:03 ` Mel Gorman [this message]
2021-10-14 15:45 ` Vlastimil Babka
2021-10-08 13:53 ` [PATCH 4/8] mm/writeback: Throttle based on page writeback instead of congestion Mel Gorman
2021-10-14 15:34 ` Vlastimil Babka
2021-10-08 13:53 ` [PATCH 5/8] mm/page_alloc: Remove the throttling logic from the page allocator Mel Gorman
2021-10-14 15:36 ` Vlastimil Babka
2021-10-08 13:53 ` [PATCH 6/8] mm/vmscan: Centralise timeout values for reclaim_throttle Mel Gorman
2021-10-14 15:38 ` Vlastimil Babka
2021-10-08 13:53 ` [PATCH 7/8] mm/vmscan: Increase the timeout if page reclaim is not making progress Mel Gorman
2021-10-14 15:39 ` Vlastimil Babka
2021-10-08 13:53 ` [PATCH 8/8] mm/vmscan: Delay waking of tasks throttled on NOPROGRESS Mel Gorman
2021-10-14 15:41 ` Vlastimil Babka
2021-10-19 9:01 [PATCH v4 0/8] Remove dependency on congestion_wait in mm/ Mel Gorman
2021-10-19 9:01 ` [PATCH 3/8] mm/vmscan: Throttle reclaim when no progress is being made Mel Gorman
2021-10-22 14:46 [PATCH v5 0/8] Remove dependency on congestion_wait in mm/ Mel Gorman
2021-10-22 14:46 ` [PATCH 3/8] mm/vmscan: Throttle reclaim when no progress is being made Mel Gorman
2021-11-24 1:19 ` Darrick J. Wong
2021-11-24 1:49 ` Darrick J. Wong
2021-11-24 14:35 ` Mel Gorman
2021-11-24 18:02 ` Darrick J. Wong
2021-11-24 10:32 ` Mel Gorman
2021-11-24 10:43 ` Vlastimil Babka
2021-11-24 10:53 ` Mel Gorman
2021-11-24 17:24 ` Mike Galbraith
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