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Message-ID: <20140304002326.GA32172@lge.com>
Date: Tue, 4 Mar 2014 09:23:26 +0900
From: Joonsoo Kim <iamjoonsoo.kim@....com>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Mel Gorman <mgorman@...e.de>, Rik van Riel <riel@...hat.com>,
linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/5] compaction related commits
On Mon, Mar 03, 2014 at 12:02:00PM +0100, Vlastimil Babka wrote:
> On 02/14/2014 07:53 AM, Joonsoo Kim wrote:
> > changes for v2
> > o include more experiment data in cover letter
> > o deal with vlastimil's comments mostly about commit description on 4/5
> >
> > This patchset is related to the compaction.
> >
> > patch 1 fixes contrary implementation of the purpose of compaction.
> > patch 2~4 are for optimization.
> > patch 5 is just for clean-up.
> >
> > I tested this patchset with stress-highalloc benchmark on Mel's mmtest
> > and cannot find any regression in terms of success rate. And I find
> > much reduced(9%) elapsed time.
> >
> > Below is the average result of 10 runs on my 4GB quad core system.
> >
> > compaction-base+ is based on 3.13.0 with Vlastimil's recent fixes.
> > compaction-fix+ has this patch series on top of compaction-base+.
> >
> > Thanks.
> >
> >
> > stress-highalloc
> > 3.13.0 3.13.0
> > compaction-base+ compaction-fix+
> > Success 1 14.10 15.00
> > Success 2 20.20 20.00
> > Success 3 68.30 73.40
> >
> > 3.13.0 3.13.0
> > compaction-base+ compaction-fix+
> > User 3486.02 3437.13
> > System 757.92 741.15
> > Elapsed 1638.52 1488.32
> >
> > 3.13.0 3.13.0
> > compaction-base+ compaction-fix+
> > Minor Faults 172591561 167116621
> > Major Faults 984 859
> > Swap Ins 743 653
> > Swap Outs 3657 3535
> > Direct pages scanned 129742 127344
> > Kswapd pages scanned 1852277 1817825
> > Kswapd pages reclaimed 1838000 1804212
> > Direct pages reclaimed 129719 127327
> > Kswapd efficiency 98% 98%
> > Kswapd velocity 1130.066 1221.296
> > Direct efficiency 99% 99%
> > Direct velocity 79.367 85.585
> > Percentage direct scans 6% 6%
> > Zone normal velocity 231.829 246.097
> > Zone dma32 velocity 972.589 1055.158
> > Zone dma velocity 5.015 5.626
> > Page writes by reclaim 6287 6534
> > Page writes file 2630 2999
> > Page writes anon 3657 3535
> > Page reclaim immediate 2187 2080
> > Sector Reads 2917808 2877336
> > Sector Writes 11477891 11206722
> > Page rescued immediate 0 0
> > Slabs scanned 2214118 2168524
> > Direct inode steals 12181 9788
> > Kswapd inode steals 144830 132109
> > Kswapd skipped wait 0 0
> > THP fault alloc 0 0
> > THP collapse alloc 0 0
> > THP splits 0 0
> > THP fault fallback 0 0
> > THP collapse fail 0 0
> > Compaction stalls 738 714
> > Compaction success 194 207
> > Compaction failures 543 507
> > Page migrate success 1806083 1464014
> > Page migrate failure 0 0
> > Compaction pages isolated 3873329 3162974
> > Compaction migrate scanned 74594862 59874420
> > Compaction free scanned 125888854 110868637
> > Compaction cost 2469 1998
>
> FWIW, I've let a machine run the series with individual patches applied
> on 3.13 with my compaction patches, so 6 is the end of my series and 7-11 yours:
> The average is of 10 runs (in case you wonder how that's done, the success rates are
> calculated with a new R support that's pending Mel's merge; system time and vmstats
> are currently a hack, but I hope to add R support for them as well, and maybe publish
> to github or something if there's interest).
Good! I have an interest on it.
>
> Interestingly, you have a much lower success rate and also much lower compaction cost
> and, well, even the benchmark times. Wonder what difference in config or hw causes this.
> You seem to have THP disabled, I enabled, but that would be weird to cause this.
My 10 runs are continuous 10 runs without reboot. It makes compaction success
rate decline on every trial and therefore average result is so low than yours.
I heard that you did 10 runs because of large stdev, so I thought that continuous 10 runs
also can makes the result reliable. Therefore I decided this method although it is not
proper method to get the average. I had to notify about it. If it confuses you,
sorry about that.
Anyway, noticeable point of continuous 10 runs is that success rate decrease continuously
and significantly. I attach the rate of success 3 on every trial on below.
Base
% Success: 80
% Success: 60
% Success: 76
% Success: 74
% Success: 70
% Success: 68
% Success: 66
% Success: 65
% Success: 63
% Success: 61
Applied with my patches
% Success: 81
% Success: 78
% Success: 75
% Success: 74
% Success: 71
% Success: 72
% Success: 73
% Success: 70
% Success: 70
% Success: 70
It means that memory is fragmented continously. I didn't dig into this problem, but
it would be good subject to investigate.
Thanks.
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