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From: Dave Chinner <david@fromorbit.com>
To: Chris Mason <clm@fb.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"linux-xfs@vger.kernel.org" <linux-xfs@vger.kernel.org>,
	Roman Gushchin <guro@fb.com>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"mhocko@kernel.org" <mhocko@kernel.org>,
	"vdavydov.dev@gmail.com" <vdavydov.dev@gmail.com>
Subject: Re: [PATCH 1/2] Revert "mm: don't reclaim inodes with many attached pages"
Date: Sat, 2 Feb 2019 10:39:05 +1100
Message-ID: <20190201233905.GW6173@dastard> (raw)
In-Reply-To: <E8895615-9DDA-4FC5-A3AB-1BE593138A89@fb.com>

On Thu, Jan 31, 2019 at 03:48:11PM +0000, Chris Mason wrote:
> On 30 Jan 2019, at 20:34, Dave Chinner wrote:
> 
> > On Wed, Jan 30, 2019 at 12:21:07PM +0000, Chris Mason wrote:
> >>
> >>
> >> On 29 Jan 2019, at 23:17, Dave Chinner wrote:
> >>
> >>> From: Dave Chinner <dchinner@redhat.com>
> >>>
> >>> This reverts commit a76cf1a474d7dbcd9336b5f5afb0162baa142cf0.
> >>>
> >>> This change causes serious changes to page cache and inode cache
> >>> behaviour and balance, resulting in major performance regressions
> >>> when combining worklaods such as large file copies and kernel
> >>> compiles.
> >>>
> >>> https://bugzilla.kernel.org/show_bug.cgi?id=202441
> >>
> >> I'm a little confused by the latest comment in the bz:
> >>
> >> https://bugzilla.kernel.org/show_bug.cgi?id=202441#c24
> >
> > Which says the first patch that changed the shrinker behaviour is
> > the underlying cause of the regression.
> >
> >> Are these reverts sufficient?
> >
> > I think so.
> 
> Based on the latest comment:
> 
> "If I had been less strict in my testing I probably would have 
> discovered that the problem was present earlier than 4.19.3. Mr Gushins 
> commit made it more visible.
> I'm going back to work after two days off, so I might not be able to 
> respond inside your working hours, but I'll keep checking in on this as 
> I get a chance."
> 
> I don't think the reverts are sufficient.

Roger has tested the two reverts more heavily against 5.0.0-rc3.
Without the reverts, the machine locks up hard. With the two reverts
applied, it runs along smoothly under extremely heavy load.

https://bugzilla.kernel.org/show_bug.cgi?id=202441#c26

So, yes, these changes need to be reverted.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

  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
2019-01-31 15:48       ` Chris Mason
2019-02-01 23:39         ` Dave Chinner [this message]
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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