linux-kernel - Re: [PATCH 0/3] Reduce amount of time kswapd sleeps prematurely

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Message-ID: <20170215221532.o5rnx6wj6kfydyvv@techsingularity.net>
Date:   Wed, 15 Feb 2017 22:15:32 +0000
From:   Mel Gorman <mgorman@...hsingularity.net>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Shantanu Goel <sgoel01@...oo.com>, Chris Mason <clm@...com>,
        Johannes Weiner <hannes@...xchg.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux-MM <linux-mm@...ck.org>
Subject: Re: [PATCH 0/3] Reduce amount of time kswapd sleeps prematurely

On Wed, Feb 15, 2017 at 01:56:54PM -0800, Andrew Morton wrote:
> On Wed, 15 Feb 2017 21:29:06 +0000 Mel Gorman <mgorman@...hsingularity.net> wrote:
> 
> > On Wed, Feb 15, 2017 at 12:30:55PM -0800, Andrew Morton wrote:
> > > On Wed, 15 Feb 2017 09:22:44 +0000 Mel Gorman <mgorman@...hsingularity.net> wrote:
> > > 
> > > > This patchset is based on mmots as of Feb 9th, 2016. The baseline is
> > > > important as there are a number of kswapd-related fixes in that tree and
> > > > a comparison against v4.10-rc7 would be almost meaningless as a result.
> > > 
> > > It's very late to squeeze this into 4.10.  We can make it 4.11 material
> > > and perhaps tag it for backporting into 4.10.1?
> > 
> > It would be important that Johannes's patches go along with then because
> > I'm relied on Johannes' fixes to deal with pages being inappropriately
> > written back from reclaim context when I was analysing the workload.
> > I'm thinking specifically about these patches
> > 
> > mm-vmscan-scan-dirty-pages-even-in-laptop-mode.patch
> > mm-vmscan-kick-flushers-when-we-encounter-dirty-pages-on-the-lru.patch
> > mm-vmscan-kick-flushers-when-we-encounter-dirty-pages-on-the-lru-fix.patch
> > mm-vmscan-remove-old-flusher-wakeup-from-direct-reclaim-path.patch
> > mm-vmscan-only-write-dirty-pages-that-the-scanner-has-seen-twice.patch
> > mm-vmscan-move-dirty-pages-out-of-the-way-until-theyre-flushed.patch
> > mm-vmscan-move-dirty-pages-out-of-the-way-until-theyre-flushed-fix.patch
> > 
> > This is 4.11 material for sure but I would not automatically try merging
> > them to 4.10 unless those patches were also included, ideally with a rerun
> > of just those patches against 4.10 to make sure there are no surprises
> > lurking in there.
> 
> Head spinning a bit.  You're saying that if the three patches in the
> series "Reduce amount of time kswapd sleeps prematurely" are held off
> until 4.11 then the above 6 patches from Johannes should also be held
> off for 4.11?
> 

Not quite, sorry for the confusion. Johannes's patches stand on their
own and they are fine. I evaluated them before against 4.10-rcX and they
worked as expected.  If they go in first then these patches can go into
4.10-stable on top. If you plan to merge Johannes's patches for 4.10 or
4.10.1 then I have no problem with that whatsoever.

-- 
Mel Gorman
SUSE Labs