From: Chen Ridong <chenridong@huaweicloud.com>
To: Shakeel Butt <shakeel.butt@linux.dev>,
Johannes Weiner <hannes@cmpxchg.org>
Cc: akpm@linux-foundation.org, axelrasmussen@google.com,
yuanchu@google.com, weixugc@google.com, david@kernel.org,
lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com,
vbabka@suse.cz, rppt@kernel.org, surenb@google.com,
mhocko@suse.com, corbet@lwn.net, hannes@cmpxchg.org,
roman.gushchin@linux.dev, muchun.song@linux.dev,
yuzhao@google.com, zhengqi.arch@bytedance.com,
linux-mm@kvack.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
lujialin4@huawei.com, chenridong@huawei.com
Subject: Re: [RFC PATCH -next 1/2] mm/mglru: use mem_cgroup_iter for global reclaim
Date: Mon, 8 Dec 2025 10:26:59 +0800 [thread overview]
Message-ID: <e657d5ac-6f92-4dbb-bf32-76084988d024@huaweicloud.com> (raw)
In-Reply-To: <tvrspnhlo7x7gpjc4nn7f73b2qoyphkpaxlcnnn4fsxciv6bks@3dibvbs7u5do>
On 2025/12/5 6:29, Shakeel Butt wrote:
> Hi Chen,
>
> On Thu, Dec 04, 2025 at 12:31:23PM +0000, Chen Ridong wrote:
>> From: Chen Ridong <chenridong@huawei.com>
>>
>> The memcg LRU was originally introduced for global reclaim to enhance
>> scalability. However, its implementation complexity has led to performance
>> regressions when dealing with a large number of memory cgroups [1].
>>
>> As suggested by Johannes [1], this patch adopts mem_cgroup_iter with
>> cookie-based iteration for global reclaim, aligning with the approach
>> already used in shrink_node_memcgs. This simplification removes the
>> dedicated memcg LRU tracking while maintaining the core functionality.
>>
>> It performed a stress test based on Zhao Yu's methodology [2] on a
>> 1 TB, 4-node NUMA system. The results are summarized below:
>>
>> memcg LRU memcg iter
>> stddev(pgsteal) / mean(pgsteal) 91.2% 75.7%
>> sum(pgsteal) / sum(requested) 216.4% 230.5%
>>
>> The new implementation demonstrates a significant improvement in
>> fairness, reducing the standard deviation relative to the mean by
>> 15.5 percentage points. While the reclaim accuracy shows a slight
>> increase in overscan (from 85086871 to 90633890, 6.5%).
>>
>> The primary benefits of this change are:
>> 1. Simplified codebase by removing custom memcg LRU infrastructure
>> 2. Improved fairness in memory reclaim across multiple cgroups
>> 3. Better performance when creating many memory cgroups
>>
>> [1] https://lore.kernel.org/r/20251126171513.GC135004@cmpxchg.org
>> [2] https://lore.kernel.org/r/20221222041905.2431096-7-yuzhao@google.com
>> Signed-off-by: Chen Ridong <chenridong@huawei.com>
>
> Thanks a lot of this awesome work.
>
Hello Shakeel and Johannes,
I apologize for the incorrect results I provided earlier. I initially used an AI tool to process the
data (I admit that was lazy of me—please forget that). When I re-ran the test to re-extracted the
refault data and processed it again, I found that the AI tool had given me the wrong output.
I have now processed the data manually in Excel, and the correct results are:
pgsteal：
memcg LRU memcg iter
stddev(pgsteal) / mean(pgsteal) 106.03% 93.20%
sum(pgsteal) / sum(requested) 98.10% 99.28%
workingset_refault_anon：
memcg LRU memcg iter
stddev(refault) / mean(refault) 193.97% 134.67%
sum(refault) 1963229 2027567
I believe these final results are much better than the previous incorrect ones, especially since the
pgsteal ratio is now close to 100%, indicating we are not over-scanning. Additionally, refaults
increased by 64,238 (a 3.2% rise).
Let me know if you have any questions.
----------------------------------------------------------------------
The original data memcg LRU:
pgsteal:
SUM: 38572704 AVERAGE: 301349.25 STDEV: 319518.5965
refault:
SUM: 1963229 AVERAGE: 15337.72656 STDEV: 29750.03391
pgsteal 655392 workingset_refault_anon 17131
pgsteal 657308 workingset_refault_anon 24841
pgsteal 103777 workingset_refault_anon 430
pgsteal 103134 workingset_refault_anon 884
pgsteal 964772 workingset_refault_anon 117159
pgsteal 103462 workingset_refault_anon 539
pgsteal 102878 workingset_refault_anon 25
pgsteal 707851 workingset_refault_anon 30634
pgsteal 103925 workingset_refault_anon 497
pgsteal 103913 workingset_refault_anon 953
pgsteal 103020 workingset_refault_anon 110
pgsteal 102871 workingset_refault_anon 607
pgsteal 697775 workingset_refault_anon 21529
pgsteal 102944 workingset_refault_anon 57
pgsteal 103090 workingset_refault_anon 819
pgsteal 102988 workingset_refault_anon 583
pgsteal 102987 workingset_refault_anon 108
pgsteal 103093 workingset_refault_anon 17
pgsteal 778016 workingset_refault_anon 79000
pgsteal 102920 workingset_refault_anon 14
pgsteal 655447 workingset_refault_anon 9069
pgsteal 102869 workingset_refault_anon 6
pgsteal 699920 workingset_refault_anon 34409
pgsteal 103127 workingset_refault_anon 223
pgsteal 102876 workingset_refault_anon 646
pgsteal 103642 workingset_refault_anon 439
pgsteal 102881 workingset_refault_anon 110
pgsteal 863202 workingset_refault_anon 77605
pgsteal 651786 workingset_refault_anon 8322
pgsteal 102981 workingset_refault_anon 51
pgsteal 103380 workingset_refault_anon 877
pgsteal 706377 workingset_refault_anon 27729
pgsteal 103436 workingset_refault_anon 682
pgsteal 103839 workingset_refault_anon 336
pgsteal 103012 workingset_refault_anon 23
pgsteal 103476 workingset_refault_anon 729
pgsteal 102867 workingset_refault_anon 12
pgsteal 102914 workingset_refault_anon 122
pgsteal 102886 workingset_refault_anon 627
pgsteal 103736 workingset_refault_anon 514
pgsteal 102879 workingset_refault_anon 618
pgsteal 102860 workingset_refault_anon 3
pgsteal 102877 workingset_refault_anon 27
pgsteal 103255 workingset_refault_anon 384
pgsteal 982183 workingset_refault_anon 85362
pgsteal 102947 workingset_refault_anon 158
pgsteal 102880 workingset_refault_anon 651
pgsteal 973764 workingset_refault_anon 81542
pgsteal 923711 workingset_refault_anon 94596
pgsteal 102938 workingset_refault_anon 660
pgsteal 888882 workingset_refault_anon 69549
pgsteal 102868 workingset_refault_anon 14
pgsteal 103130 workingset_refault_anon 166
pgsteal 103388 workingset_refault_anon 467
pgsteal 102965 workingset_refault_anon 197
pgsteal 964699 workingset_refault_anon 74903
pgsteal 103263 workingset_refault_anon 373
pgsteal 103614 workingset_refault_anon 781
pgsteal 962228 workingset_refault_anon 72108
pgsteal 672174 workingset_refault_anon 19739
pgsteal 102920 workingset_refault_anon 19
pgsteal 670248 workingset_refault_anon 18411
pgsteal 102877 workingset_refault_anon 581
pgsteal 103758 workingset_refault_anon 871
pgsteal 102874 workingset_refault_anon 609
pgsteal 103075 workingset_refault_anon 274
pgsteal 103550 workingset_refault_anon 102
pgsteal 755180 workingset_refault_anon 44303
pgsteal 951252 workingset_refault_anon 84566
pgsteal 929144 workingset_refault_anon 99081
pgsteal 103207 workingset_refault_anon 30
pgsteal 103292 workingset_refault_anon 427
pgsteal 103271 workingset_refault_anon 332
pgsteal 102865 workingset_refault_anon 4
pgsteal 923280 workingset_refault_anon 72715
pgsteal 104682 workingset_refault_anon 372
pgsteal 102870 workingset_refault_anon 7
pgsteal 102902 workingset_refault_anon 661
pgsteal 103053 workingset_refault_anon 40
pgsteal 103685 workingset_refault_anon 540
pgsteal 103857 workingset_refault_anon 970
pgsteal 109210 workingset_refault_anon 2806
pgsteal 103627 workingset_refault_anon 319
pgsteal 104029 workingset_refault_anon 42
pgsteal 918361 workingset_refault_anon 90387
pgsteal 103489 workingset_refault_anon 626
pgsteal 103188 workingset_refault_anon 801
pgsteal 102875 workingset_refault_anon 11
pgsteal 102994 workingset_refault_anon 79
pgsteal 102910 workingset_refault_anon 43
pgsteal 102922 workingset_refault_anon 687
pgsteal 103941 workingset_refault_anon 1219
pgsteal 903622 workingset_refault_anon 113751
pgsteal 664357 workingset_refault_anon 27959
pgsteal 104947 workingset_refault_anon 11
pgsteal 701084 workingset_refault_anon 30665
pgsteal 650719 workingset_refault_anon 20810
pgsteal 641924 workingset_refault_anon 17137
pgsteal 933870 workingset_refault_anon 98393
pgsteal 633231 workingset_refault_anon 15924
pgsteal 102936 workingset_refault_anon 34
pgsteal 104020 workingset_refault_anon 781
pgsteal 104274 workingset_refault_anon 1841
pgsteal 621672 workingset_refault_anon 5891
pgsteal 103307 workingset_refault_anon 474
pgsteal 103386 workingset_refault_anon 27
pgsteal 103266 workingset_refault_anon 243
pgsteal 102896 workingset_refault_anon 15
pgsteal 103905 workingset_refault_anon 988
pgsteal 103104 workingset_refault_anon 304
pgsteal 104277 workingset_refault_anon 285
pgsteal 696374 workingset_refault_anon 24971
pgsteal 103009 workingset_refault_anon 775
pgsteal 103849 workingset_refault_anon 747
pgsteal 102867 workingset_refault_anon 9
pgsteal 700211 workingset_refault_anon 35289
pgsteal 102923 workingset_refault_anon 88
pgsteal 104139 workingset_refault_anon 789
pgsteal 105152 workingset_refault_anon 1257
pgsteal 102945 workingset_refault_anon 76
pgsteal 103227 workingset_refault_anon 343
pgsteal 102880 workingset_refault_anon 95
pgsteal 102967 workingset_refault_anon 101
pgsteal 989176 workingset_refault_anon 89597
pgsteal 694181 workingset_refault_anon 22499
pgsteal 784354 workingset_refault_anon 68311
pgsteal 102882 workingset_refault_anon 24
pgsteal 103108 workingset_refault_anon 24
-------------------------------------------------------------------
The original data memcg iter:
pgsteal:
SUM: 39036863 AVERAGE: 304975.4922 STDEV: 284226.526
refault:
SUM: 2027567 AVERAGE: 15840.36719 STDEV: 21332.00262
pgsteal 103167 workingset_refault_anon 203
pgsteal 714044 workingset_refault_anon 42633
pgsteal 103209 workingset_refault_anon 581
pgsteal 103605 workingset_refault_anon 240
pgsteal 740909 workingset_refault_anon 53177
pgsteal 103089 workingset_refault_anon 141
pgsteal 726760 workingset_refault_anon 32624
pgsteal 104039 workingset_refault_anon 397
pgsteal 754667 workingset_refault_anon 56144
pgsteal 713916 workingset_refault_anon 41813
pgsteal 104104 workingset_refault_anon 307
pgsteal 109567 workingset_refault_anon 244
pgsteal 714194 workingset_refault_anon 47076
pgsteal 711693 workingset_refault_anon 35616
pgsteal 105026 workingset_refault_anon 2221
pgsteal 103442 workingset_refault_anon 269
pgsteal 112773 workingset_refault_anon 5086
pgsteal 715969 workingset_refault_anon 32457
pgsteal 127828 workingset_refault_anon 9579
pgsteal 102885 workingset_refault_anon 109
pgsteal 112156 workingset_refault_anon 2974
pgsteal 104242 workingset_refault_anon 948
pgsteal 701184 workingset_refault_anon 47940
pgsteal 104080 workingset_refault_anon 836
pgsteal 106606 workingset_refault_anon 2420
pgsteal 103666 workingset_refault_anon 129
pgsteal 103330 workingset_refault_anon 532
pgsteal 103639 workingset_refault_anon 275
pgsteal 108494 workingset_refault_anon 3814
pgsteal 103626 workingset_refault_anon 412
pgsteal 103697 workingset_refault_anon 577
pgsteal 103736 workingset_refault_anon 582
pgsteal 103360 workingset_refault_anon 281
pgsteal 116733 workingset_refault_anon 6674
pgsteal 102978 workingset_refault_anon 5
pgsteal 108945 workingset_refault_anon 3141
pgsteal 706630 workingset_refault_anon 33241
pgsteal 103426 workingset_refault_anon 134
pgsteal 715070 workingset_refault_anon 33575
pgsteal 102871 workingset_refault_anon 12
pgsteal 103617 workingset_refault_anon 776
pgsteal 767084 workingset_refault_anon 64710
pgsteal 104197 workingset_refault_anon 176
pgsteal 104488 workingset_refault_anon 1469
pgsteal 103253 workingset_refault_anon 228
pgsteal 702800 workingset_refault_anon 26424
pgsteal 107469 workingset_refault_anon 2838
pgsteal 104441 workingset_refault_anon 1562
pgsteal 123013 workingset_refault_anon 13117
pgsteal 737817 workingset_refault_anon 53330
pgsteal 103939 workingset_refault_anon 759
pgsteal 103568 workingset_refault_anon 783
pgsteal 122707 workingset_refault_anon 11944
pgsteal 103690 workingset_refault_anon 885
pgsteal 103456 workingset_refault_anon 145
pgsteal 104068 workingset_refault_anon 632
pgsteal 319368 workingset_refault_anon 12579
pgsteal 103912 workingset_refault_anon 304
pgsteal 119416 workingset_refault_anon 3350
pgsteal 717107 workingset_refault_anon 34764
pgsteal 107163 workingset_refault_anon 535
pgsteal 103299 workingset_refault_anon 142
pgsteal 103825 workingset_refault_anon 176
pgsteal 408564 workingset_refault_anon 14606
pgsteal 115785 workingset_refault_anon 4622
pgsteal 119234 workingset_refault_anon 9225
pgsteal 729060 workingset_refault_anon 54309
pgsteal 107149 workingset_refault_anon 536
pgsteal 708839 workingset_refault_anon 43133
pgsteal 695961 workingset_refault_anon 40182
pgsteal 723303 workingset_refault_anon 32298
pgsteal 103581 workingset_refault_anon 1305
pgsteal 699646 workingset_refault_anon 49924
pgsteal 717867 workingset_refault_anon 39229
pgsteal 104148 workingset_refault_anon 1318
pgsteal 104127 workingset_refault_anon 568
pgsteal 103168 workingset_refault_anon 322
pgsteal 103477 workingset_refault_anon 538
pgsteal 103022 workingset_refault_anon 60
pgsteal 103305 workingset_refault_anon 323
pgsteal 103812 workingset_refault_anon 1324
pgsteal 103139 workingset_refault_anon 126
pgsteal 723251 workingset_refault_anon 34206
pgsteal 103068 workingset_refault_anon 861
pgsteal 742515 workingset_refault_anon 54439
pgsteal 762161 workingset_refault_anon 52654
pgsteal 103934 workingset_refault_anon 889
pgsteal 104065 workingset_refault_anon 315
pgsteal 383893 workingset_refault_anon 25036
pgsteal 107929 workingset_refault_anon 2367
pgsteal 726127 workingset_refault_anon 45809
pgsteal 675291 workingset_refault_anon 66534
pgsteal 105585 workingset_refault_anon 2323
pgsteal 105098 workingset_refault_anon 1625
pgsteal 104264 workingset_refault_anon 718
pgsteal 741873 workingset_refault_anon 47045
pgsteal 103466 workingset_refault_anon 70
pgsteal 723870 workingset_refault_anon 58780
pgsteal 104740 workingset_refault_anon 521
pgsteal 740739 workingset_refault_anon 45099
pgsteal 752994 workingset_refault_anon 53713
pgsteal 110164 workingset_refault_anon 2572
pgsteal 711304 workingset_refault_anon 41135
pgsteal 746870 workingset_refault_anon 60298
pgsteal 729166 workingset_refault_anon 42594
pgsteal 110138 workingset_refault_anon 1511
pgsteal 103836 workingset_refault_anon 675
pgsteal 116821 workingset_refault_anon 3952
pgsteal 104967 workingset_refault_anon 2035
pgsteal 711362 workingset_refault_anon 31458
pgsteal 103835 workingset_refault_anon 507
pgsteal 113846 workingset_refault_anon 2997
pgsteal 104406 workingset_refault_anon 1724
pgsteal 103551 workingset_refault_anon 1293
pgsteal 705340 workingset_refault_anon 44234
pgsteal 728076 workingset_refault_anon 29849
pgsteal 103829 workingset_refault_anon 254
pgsteal 103700 workingset_refault_anon 712
pgsteal 103382 workingset_refault_anon 506
pgsteal 728881 workingset_refault_anon 60152
pgsteal 614645 workingset_refault_anon 43956
pgsteal 107672 workingset_refault_anon 2768
pgsteal 123550 workingset_refault_anon 11937
pgsteal 103747 workingset_refault_anon 899
pgsteal 747657 workingset_refault_anon 50264
pgsteal 110949 workingset_refault_anon 1422
pgsteal 103596 workingset_refault_anon 278
pgsteal 742471 workingset_refault_anon 69586
--
Best regards,
Ridong
next prev parent reply other threads:[~2025-12-08 2:27 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-04 12:31 [RFC PATCH -next 0/2] mm/mglru: remove memcg lru Chen Ridong
2025-12-04 12:31 ` [RFC PATCH -next 1/2] mm/mglru: use mem_cgroup_iter for global reclaim Chen Ridong
2025-12-04 18:28 ` Johannes Weiner
2025-12-04 22:29 ` Shakeel Butt
2025-12-08 2:26 ` Chen Ridong [this message]
2025-12-08 3:10 ` Chen Ridong
2025-12-04 12:31 ` [RFC PATCH -next 2/2] mm/mglru: remove memcg lru Chen Ridong
2025-12-04 18:34 ` Johannes Weiner
2025-12-05 2:57 ` [RFC PATCH -next 1/2] mm/mglru: use mem_cgroup_iter for global reclaim zhongjinji
2025-12-08 2:35 ` Chen Ridong
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=e657d5ac-6f92-4dbb-bf32-76084988d024@huaweicloud.com \
--to=chenridong@huaweicloud.com \
--cc=Liam.Howlett@oracle.com \
--cc=akpm@linux-foundation.org \
--cc=axelrasmussen@google.com \
--cc=cgroups@vger.kernel.org \
--cc=chenridong@huawei.com \
--cc=corbet@lwn.net \
--cc=david@kernel.org \
--cc=hannes@cmpxchg.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=lorenzo.stoakes@oracle.com \
--cc=lujialin4@huawei.com \
--cc=mhocko@suse.com \
--cc=muchun.song@linux.dev \
--cc=roman.gushchin@linux.dev \
--cc=rppt@kernel.org \
--cc=shakeel.butt@linux.dev \
--cc=surenb@google.com \
--cc=vbabka@suse.cz \
--cc=weixugc@google.com \
--cc=yuanchu@google.com \
--cc=yuzhao@google.com \
--cc=zhengqi.arch@bytedance.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox