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From: Wolfgang Walter <linux@stwm.de>
To: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>, Roman Gushchin <guro@fb.com>,
	Michal Hocko <mhocko@kernel.org>, Chris Mason <clm@fb.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org,
	akpm@linux-foundation.org, vdavydov.dev@gmail.com
Subject: Re: [PATCH 1/2] Revert "mm: don't reclaim inodes with many attached pages"
Date: Mon, 11 Feb 2019 16:34:34 +0100
Message-ID: <2582452.8YSf1DXvRS@stwm.de> (raw)
In-Reply-To: <20190207102750.GA4570@quack2.suse.cz>

Am Donnerstag, 7. Februar 2019, 11:27:50 schrieb Jan Kara:
> On Fri 01-02-19 09:19:04, Dave Chinner wrote:
> > Maybe for memcgs, but that's exactly the oppose of what we want to
> > do for global caches (e.g. filesystem metadata caches). We need to
> > make sure that a single, heavily pressured cache doesn't evict small
> > caches that lower pressure but are equally important for
> > performance.
> > 
> > e.g. I've noticed recently a significant increase in RMW cycles in
> > XFS inode cache writeback during various benchmarks. It hasn't
> > affected performance because the machine has IO and CPU to burn, but
> > on slower machines and storage, it will have a major impact.
> 
> Just as a data point, our performance testing infrastructure has bisected
> down to the commits discussed in this thread as the cause of about 40%
> regression in XFS file delete performance in bonnie++ benchmark.

We also bisected our big IO-performance problem of an imap-server (starting 
with 4.19.3) down to

	mm: don't reclaim inodes with many attached pages
	commit a76cf1a474d7dbcd9336b5f5afb0162baa142cf0 upstream.

On other servers the filesystems sometimes seems to hang for 10 seconds and 
more.

We also see a performance regression compared to 4.14 even with this patch 
reverted, but much less dramatic.

Now I saw this thread and I'll try to revert

172b06c32b949759fe6313abec514bc4f15014f4

and see if this helps.

Regards,
-- 
Wolfgang Walter
Studentenwerk München
Anstalt des öffentlichen Rechts

  parent reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-30  4:17 [PATCH 0/2] [REGRESSION v4.19-20] mm: shrinkers are now way too aggressive Dave Chinner
2019-01-30  4:17 ` [PATCH 1/2] Revert "mm: don't reclaim inodes with many attached pages" Dave Chinner
2019-01-30 12:21   ` Chris Mason
2019-01-31  1:34     ` Dave Chinner
2019-01-31  9:10       ` Michal Hocko
2019-01-31 18:57         ` Roman Gushchin
2019-01-31 22:19           ` Dave Chinner
2019-02-04 21:47             ` Dave Chinner
2019-02-07 10:27             ` Jan Kara
2019-02-08  5:37               ` Andrew Morton
2019-02-08  9:55                 ` Jan Kara
2019-02-08 12:50                   ` Jan Kara
2019-02-08 22:49                     ` Andrew Morton
2019-02-09  3:42                       ` Roman Gushchin
2019-02-08 21:25                 ` Dave Chinner
2019-02-11 15:34               ` Wolfgang Walter [this message]
2019-01-31 15:48       ` Chris Mason
2019-02-01 23:39         ` Dave Chinner
2019-01-30  4:17 ` [PATCH 2/2] Revert "mm: slowly shrink slabs with a relatively small number of objects" Dave Chinner
2019-01-30  5:48 ` [PATCH 0/2] [REGRESSION v4.19-20] mm: shrinkers are now way too aggressive Roman Gushchin

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