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Date: Wed, 3 Jun 2020 14:46:48 +0900
From: Joonsoo Kim <js1304@...il.com>
To: Suren Baghdasaryan <surenb@...gle.com>
Cc: Vlastimil Babka <vbabka@...e.cz>,
Andrew Morton <akpm@...ux-foundation.org>,
Linux Memory Management List <linux-mm@...ck.org>,
LKML <linux-kernel@...r.kernel.org>,
Johannes Weiner <hannes@...xchg.org>,
Michal Hocko <mhocko@...nel.org>,
Hugh Dickins <hughd@...gle.com>,
Minchan Kim <minchan@...nel.org>,
Mel Gorman <mgorman@...hsingularity.net>, kernel-team@....com,
Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH v5 00/10] workingset protection/detection on the anonymous
LRU list
2020년 6월 3일 (수) 오후 12:57, Suren Baghdasaryan <surenb@...gle.com>님이 작성:
>
> On Wed, Apr 8, 2020 at 5:50 PM Joonsoo Kim <js1304@...il.com> wrote:
> >
> > 2020년 4월 9일 (목) 오전 1:55, Vlastimil Babka <vbabka@...e.cz>님이 작성:
> > >
> > > On 4/3/20 7:40 AM, js1304@...il.com wrote:
> > > > From: Joonsoo Kim <iamjoonsoo.kim@....com>
> > > >
> > > > Hello,
> > > >
> > > > This patchset implements workingset protection and detection on
> > > > the anonymous LRU list.
> > >
> > > Hi!
> >
> > Hi!
> >
> > > > I did another test to show the performance effect of this patchset.
> > > >
> > > > - ebizzy (with modified random function)
> > > > ebizzy is the test program that main thread allocates lots of memory and
> > > > child threads access them randomly during the given times. Swap-in/out
> > > > will happen if allocated memory is larger than the system memory.
> > > >
> > > > The random function that represents the zipf distribution is used to
> > > > make hot/cold memory. Hot/cold ratio is controlled by the parameter. If
> > > > the parameter is high, hot memory is accessed much larger than cold one.
> > > > If the parameter is low, the number of access on each memory would be
> > > > similar. I uses various parameters in order to show the effect of
> > > > patchset on various hot/cold ratio workload.
> > > >
> > > > My test setup is a virtual machine with 8 cpus and 1024MB memory.
> > > >
> > > > Result format is as following.
> > > >
> > > > Parameter 0.1 ... 1.3
> > > > Allocated memory size
> > > > Throughput for base (larger is better)
> > > > Throughput for patchset (larger is better)
> > > > Improvement (larger is better)
> > > >
> > > >
> > > > * single thread
> > > >
> > > > 0.1 0.3 0.5 0.7 0.9 1.1 1.3
> > > > <512M>
> > > > 7009.0 7372.0 7774.0 8523.0 9569.0 10724.0 11936.0
> > > > 6973.0 7342.0 7745.0 8576.0 9441.0 10730.0 12033.0
> > > > -0.01 -0.0 -0.0 0.01 -0.01 0.0 0.01
> > > > <768M>
> > > > 915.0 1039.0 1275.0 1687.0 2328.0 3486.0 5445.0
> > > > 920.0 1037.0 1238.0 1689.0 2384.0 3638.0 5381.0
> > > > 0.01 -0.0 -0.03 0.0 0.02 0.04 -0.01
> > > > <1024M>
> > > > 425.0 471.0 539.0 753.0 1183.0 2130.0 3839.0
> > > > 414.0 468.0 553.0 770.0 1242.0 2187.0 3932.0
> > > > -0.03 -0.01 0.03 0.02 0.05 0.03 0.02
> > > > <1280M>
> > > > 320.0 346.0 410.0 556.0 871.0 1654.0 3298.0
> > > > 316.0 346.0 411.0 550.0 892.0 1652.0 3293.0
> > > > -0.01 0.0 0.0 -0.01 0.02 -0.0 -0.0
> > > > <1536M>
> > > > 273.0 290.0 341.0 458.0 733.0 1381.0 2925.0
> > > > 271.0 293.0 344.0 462.0 740.0 1398.0 2969.0
> > > > -0.01 0.01 0.01 0.01 0.01 0.01 0.02
> > > > <2048M>
> > > > 77.0 79.0 95.0 147.0 276.0 690.0 1816.0
> > > > 91.0 94.0 115.0 170.0 321.0 770.0 2018.0
> > > > 0.18 0.19 0.21 0.16 0.16 0.12 0.11
> > > >
> > > >
> > > > * multi thread (8)
> > > >
> > > > 0.1 0.3 0.5 0.7 0.9 1.1 1.3
> > > > <512M>
> > > > 29083.0 29648.0 30145.0 31668.0 33964.0 38414.0 43707.0
> > > > 29238.0 29701.0 30301.0 31328.0 33809.0 37991.0 43667.0
> > > > 0.01 0.0 0.01 -0.01 -0.0 -0.01 -0.0
> > > > <768M>
> > > > 3332.0 3699.0 4673.0 5830.0 8307.0 12969.0 17665.0
> > > > 3579.0 3992.0 4432.0 6111.0 8699.0 12604.0 18061.0
> > > > 0.07 0.08 -0.05 0.05 0.05 -0.03 0.02
> > > > <1024M>
> > > > 1921.0 2141.0 2484.0 3296.0 5391.0 8227.0 14574.0
> > > > 1989.0 2155.0 2609.0 3565.0 5463.0 8170.0 15642.0
> > > > 0.04 0.01 0.05 0.08 0.01 -0.01 0.07
> > > > <1280M>
> > > > 1524.0 1625.0 1931.0 2581.0 4155.0 6959.0 12443.0
> > > > 1560.0 1707.0 2016.0 2714.0 4262.0 7518.0 13910.0
> > > > 0.02 0.05 0.04 0.05 0.03 0.08 0.12
> > > > <1536M>
> > > > 1303.0 1399.0 1550.0 2137.0 3469.0 6712.0 12944.0
> > > > 1356.0 1465.0 1701.0 2237.0 3583.0 6830.0 13580.0
> > > > 0.04 0.05 0.1 0.05 0.03 0.02 0.05
> > > > <2048M>
> > > > 172.0 184.0 215.0 289.0 514.0 1318.0 4153.0
> > > > 175.0 190.0 225.0 329.0 606.0 1585.0 5170.0
> > > > 0.02 0.03 0.05 0.14 0.18 0.2 0.24
> > > >
> > > > As we can see, as allocated memory grows, patched kernel get the better
> > > > result. Maximum improvement is 21% for the single thread test and
> > > > 24% for the multi thread test.
> > >
> > > So, these results seem to be identical since v1. After the various changes up to
> > > v5, should the benchmark be redone? And was that with a full patchset or
> > > patches 1+2?
> >
> > It was done with a full patchset. I think that these results would not
> > be changed
> > even on v5 since it is improvement from the concept of this patchset and
> > implementation detail doesn't much matter. However, I will redo.
> >
> > > > * EXPERIMENT
> > > > I made a test program to imitates above scenario and confirmed that
> > > > problem exists. Then, I checked that this patchset fixes it.
> > > >
> > > > My test setup is a virtual machine with 8 cpus and 6100MB memory. But,
> > > > the amount of the memory that the test program can use is about 280 MB.
> > > > This is because the system uses large ram-backed swap and large ramdisk
> > > > to capture the trace.
> > > >
> > > > Test scenario is like as below.
> > > >
> > > > 1. allocate cold memory (512MB)
> > > > 2. allocate hot-1 memory (96MB)
> > > > 3. activate hot-1 memory (96MB)
> > > > 4. allocate another hot-2 memory (96MB)
> > > > 5. access cold memory (128MB)
> > > > 6. access hot-2 memory (96MB)
> > > > 7. repeat 5, 6
> > > >
> > > > Since hot-1 memory (96MB) is on the active list, the inactive list can
> > > > contains roughly 190MB pages. hot-2 memory's re-access interval
> > > > (96+128 MB) is more 190MB, so it cannot be promoted without workingset
> > > > detection and swap-in/out happens repeatedly. With this patchset,
> > > > workingset detection works and promotion happens. Therefore, swap-in/out
> > > > occurs less.
> > > >
> > > > Here is the result. (average of 5 runs)
> > > >
> > > > type swap-in swap-out
> > > > base 863240 989945
> > > > patch 681565 809273
> > > >
> > > > As we can see, patched kernel do less swap-in/out.
> > >
> > > Same comment, also v1 has this note:
> >
> > I had tested this scenario on every version of the patchset and found the same
> > trend.
> >
> > > > Note that, this result is gotten from v5.1. Although workingset detection
> > > > works on v5.1, it doesn't work well on v5.5. It looks like that recent
> > > > code change on workingset.c is the reason of this problem. I will
> > > > track it soon.
> > > What was the problem then, assuming it's fixed? Maybe I just missed it
> > > mentioned. Can results now be gathered on 5.6?
> >
> > It was fixed on v2. Change log on v2 "fix a critical bug that uses out of index
> > lru list in workingset_refault()" is for this problem. I should note
> > that clearly.
> >
> > > In general, this patchset seems to be doing the right thing. I haven't reviewed
> > > the code yet, but hope to do so soon. But inevitably, with any changes in this
> > > area there will be workloads that will suffer instead of benefit. That can be
> > > because we are actually doing a wrong thing, or there's a bug in the code, or
> > > the workloads happen to benefit from the current behavior even if it's not the
> > > generally optimal one. And I'm afraid only testing on a variety of workloads can
> > > show that. You mentioned somewhere that your production workloads benefit? Can
> > > it be quantified more? Could e.g. Johannes test this a bit at Facebook, or
> >
> > I cannot share the detail of the test for my production (smart TV)
> > workload. Roughly,
> > it is repeat of various action and app (channel change, volume change,
> > youtube, etc.)
> > on smart TV and it is memory stress test. Result after the workload is:
> >
> > base
> > pswpin 328211
> > pswpout 304015
> >
> > patched
> > pswpin 261884
> > pswpout 276062
> >
> > So, improvement on pswpin and pswpout is roughly 20% and 9%, respectively.
> >
> > > it be quantified more? Could e.g. Johannes test this a bit at Facebook, or
> > > somebody at Google?
> >
> > It's really helpful if someone else could test this on their workload.
>
> Please let me know when the new version (after Johannes' memcg
> charging changes) is available for testing. I'll try them on Android
> workload.
> Thanks.
I have a new version after Johannes' memcg charging changes but now
MM tree has another changes on this area ("mm: balance LRU lists based on
relative thrashing v2") so I need to rebase on it. I guess that at
least two weaks
are required.
Thanks.
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