[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <97419aca-af5f-4328-84dc-c97bb73ca1ac@redhat.com>
Date: Thu, 7 Aug 2025 12:21:18 +0200
From: David Hildenbrand <david@...hat.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
kernel test robot <oliver.sang@...el.com>
Cc: Dev Jain <dev.jain@....com>, oe-lkp@...ts.linux.dev, lkp@...el.com,
linux-kernel@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>,
Barry Song <baohua@...nel.org>, Pedro Falcato <pfalcato@...e.de>,
Anshuman Khandual <anshuman.khandual@....com>,
Bang Li <libang.li@...group.com>, Baolin Wang
<baolin.wang@...ux.alibaba.com>, bibo mao <maobibo@...ngson.cn>,
Hugh Dickins <hughd@...gle.com>, Ingo Molnar <mingo@...nel.org>,
Jann Horn <jannh@...gle.com>, Lance Yang <ioworker0@...il.com>,
Liam Howlett <liam.howlett@...cle.com>, Matthew Wilcox
<willy@...radead.org>, Peter Xu <peterx@...hat.com>,
Qi Zheng <zhengqi.arch@...edance.com>, Ryan Roberts <ryan.roberts@....com>,
Vlastimil Babka <vbabka@...e.cz>, Yang Shi <yang@...amperecomputing.com>,
Zi Yan <ziy@...dia.com>, linux-mm@...ck.org
Subject: Re: [linus:master] [mm] f822a9a81a:
stress-ng.bigheap.realloc_calls_per_sec 37.3% regression
On 07.08.25 10:27, Lorenzo Stoakes wrote:
> On Thu, Aug 07, 2025 at 04:17:09PM +0800, kernel test robot wrote:
>>
>>
>> Hello,
>>
>> kernel test robot noticed a 37.3% regression of stress-ng.bigheap.realloc_calls_per_sec on:
>>
>
> Dev - could you please investigate and provide a fix for this as a
> priority? As these numbers are quite scary (unless they're somehow super
> synthetic or not meaningful or something).
>
>>
>> commit: f822a9a81a31311d67f260aea96005540b18ab07 ("mm: optimize mremap() by PTE batching")
>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
>>
>> [still regression on linus/master 186f3edfdd41f2ae87fc40a9ccba52a3bf930994]
>> [still regression on linux-next/master b9ddaa95fd283bce7041550ddbbe7e764c477110]
>>
>> testcase: stress-ng
>> config: x86_64-rhel-9.4
>> compiler: gcc-12
>> test machine: 192 threads 2 sockets Intel(R) Xeon(R) Platinum 8468V CPU @ 2.4GHz (Sapphire Rapids) with 384G memory
>> parameters:
>>
>> nr_threads: 100%
>> testtime: 60s
>> test: bigheap
>> cpufreq_governor: performance
>>
>>
>>
>>
>> If you fix the issue in a separate patch/commit (i.e. not just a new version of
>> the same patch/commit), kindly add following tags
>> | Reported-by: kernel test robot <oliver.sang@...el.com>
>> | Closes: https://lore.kernel.org/oe-lkp/202508071609.4e743d7c-lkp@intel.com
>>
>>
>> Details are as below:
>> -------------------------------------------------------------------------------------------------->
>>
>>
>> The kernel config and materials to reproduce are available at:
>> https://download.01.org/0day-ci/archive/20250807/202508071609.4e743d7c-lkp@intel.com
>>
>> =========================================================================================
>> compiler/cpufreq_governor/kconfig/nr_threads/rootfs/tbox_group/test/testcase/testtime:
>> gcc-12/performance/x86_64-rhel-9.4/100%/debian-12-x86_64-20240206.cgz/igk-spr-2sp1/bigheap/stress-ng/60s
>>
>> commit:
>> 94dab12d86 ("mm: call pointers to ptes as ptep")
>> f822a9a81a ("mm: optimize mremap() by PTE batching")
>>
>> 94dab12d86cf77ff f822a9a81a31311d67f260aea96
>> ---------------- ---------------------------
>> %stddev %change %stddev
>> \ | \
>> 13777 ± 37% +45.0% 19979 ± 27% numa-vmstat.node1.nr_slab_reclaimable
>> 367205 +2.3% 375703 vmstat.system.in
>> 55106 ± 37% +45.1% 79971 ± 27% numa-meminfo.node1.KReclaimable
>> 55106 ± 37% +45.1% 79971 ± 27% numa-meminfo.node1.SReclaimable
>> 559381 -37.3% 350757 stress-ng.bigheap.realloc_calls_per_sec
>> 11468 +1.2% 11603 stress-ng.time.system_time
>> 296.25 +4.5% 309.70 stress-ng.time.user_time
>> 0.81 ±187% -100.0% 0.00 perf-sched.sch_delay.avg.ms.__cond_resched.zap_pte_range.zap_pmd_range.isra.0
>> 9.36 ±165% -100.0% 0.00 perf-sched.sch_delay.max.ms.__cond_resched.zap_pte_range.zap_pmd_range.isra.0
>> 0.81 ±187% -100.0% 0.00 perf-sched.wait_time.avg.ms.__cond_resched.zap_pte_range.zap_pmd_range.isra.0
>> 9.36 ±165% -100.0% 0.00 perf-sched.wait_time.max.ms.__cond_resched.zap_pte_range.zap_pmd_range.isra.0
>> 5.50 ± 17% +390.9% 27.00 ± 56% perf-c2c.DRAM.local
>> 388.50 ± 10% +114.7% 834.17 ± 33% perf-c2c.DRAM.remote
>> 1214 ± 13% +107.3% 2517 ± 31% perf-c2c.HITM.local
>> 135.00 ± 19% +130.9% 311.67 ± 32% perf-c2c.HITM.remote
>> 1349 ± 13% +109.6% 2829 ± 31% perf-c2c.HITM.total
>
> Yeah this also looks pretty consistent too...
It almost looks like some kind of NUMA effects?
I would have expected that it's the overhead of the vm_normal_folio(),
but not sure how that corresponds to the SLAB + local vs. remote stats.
Maybe they are just noise?
--
Cheers,
David / dhildenb
Powered by blists - more mailing lists