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SubjectRe: [mm] 87eaceb3fa: stress-ng.madvise.ops_per_sec -19.6% regression
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On 9/30/19 1:46 AM, kernel test robot wrote:
> Greeting,
>
> FYI, we noticed a -19.6% regression of stress-ng.madvise.ops_per_sec due to commit:
>
>
> commit: 87eaceb3faa59b9b4d940ec9554ce251325d83fe ("mm: thp: make deferred split shrinker memcg aware")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
>
> in testcase: stress-ng
> on test machine: 72 threads Intel(R) Xeon(R) Gold 6140 CPU @ 2.30GHz with 192G memory
> with following parameters:
>
> nr_threads: 100%
> disk: 1HDD
> testtime: 1s
> class: vm
> ucode: 0x200005e
> cpufreq_governor: performance

Thanks for reporting the case. I did the same test on my VM (24 threads,
48GB), I saw average ~3% degradation. The test itself may have 15%
variation in the same environment according to my test, so I compared
the average result within 10 runs.

In 5.3 the deferred split queue is per node, currently it is per memcg.
If the test is run in default memcg configuration (just one root memcg),
the lock contention may get worse (two locks -> one lock).

Actually, I already noticed this issue in a different way. The patch
changed its NUMA awareness. The global kswapd may end up reclaiming THPs
from a different node.

I already came up with a patch which moves deferred split queue to
memcg->nodeinfo[] to restore NUMA awareness and keep it memcg aware at
the mean time. The same test shows average ~4% improvement and slightly
better than 5.3 with this patch.

I'm going to post the patch to the mailing list soon.

>
>
>
>
> If you fix the issue, kindly add following tag
> Reported-by: kernel test robot <rong.a.chen@intel.com>
>
>
> Details are as below:
> -------------------------------------------------------------------------------------------------->
>
>
> To reproduce:
>
> git clone https://github.com/intel/lkp-tests.git
> cd lkp-tests
> bin/lkp install job.yaml # job file is attached in this email
> bin/lkp run job.yaml
>
> =========================================================================================
> class/compiler/cpufreq_governor/disk/kconfig/nr_threads/rootfs/tbox_group/testcase/testtime/ucode:
> vm/gcc-7/performance/1HDD/x86_64-rhel-7.6/100%/debian-x86_64-2019-05-14.cgz/lkp-skl-2sp8/stress-ng/1s/0x200005e
>
> commit:
> 0a432dcbeb ("mm: shrinker: make shrinker not depend on memcg kmem")
> 87eaceb3fa ("mm: thp: make deferred split shrinker memcg aware")
>
> 0a432dcbeb32edcd 87eaceb3faa59b9b4d940ec9554
> ---------------- ---------------------------
> %stddev %change %stddev
> \ | \
> 6457 -19.5% 5198 stress-ng.madvise.ops
> 6409 -19.6% 5154 stress-ng.madvise.ops_per_sec
> 3575 -26.8% 2618 ± 6% stress-ng.mremap.ops
> 3575 -26.9% 2613 ± 6% stress-ng.mremap.ops_per_sec
> 15.77 -5.8% 14.85 ± 2% iostat.cpu.user
> 3427944 ± 4% -9.3% 3109984 meminfo.AnonPages
> 33658 ± 22% +69791.3% 23524535 ±165% sched_debug.cfs_rq:/.load.max
> 19951 ± 7% +13.3% 22611 ± 3% softirqs.CPU54.TIMER
> 109.94 -4.1% 105.41 turbostat.RAMWatt
> 5.89 ± 62% -3.1 2.78 ±173% perf-profile.calltrace.cycles-pp.page_fault
> 3.39 ±101% -0.6 2.78 ±173% perf-profile.calltrace.cycles-pp.do_page_fault.page_fault
> 3.39 ±101% -0.6 2.78 ±173% perf-profile.calltrace.cycles-pp.__do_page_fault.do_page_fault.page_fault
> 5.28 ±100% -5.3 0.00 perf-profile.children.cycles-pp.___might_sleep
> 5.28 ±100% -5.3 0.00 perf-profile.self.cycles-pp.___might_sleep
> 885704 ± 5% -11.0% 787888 ± 6% proc-vmstat.nr_anon_pages
> 1.742e+08 ± 5% -9.6% 1.576e+08 ± 2% proc-vmstat.pgalloc_normal
> 1.741e+08 ± 5% -9.6% 1.575e+08 ± 2% proc-vmstat.pgfree
> 375505 -19.4% 302688 proc-vmstat.pglazyfree
> 55236 ± 38% -55.5% 24552 ± 41% proc-vmstat.thp_deferred_split_page
> 55234 ± 38% -55.6% 24543 ± 41% proc-vmstat.thp_fault_alloc
> 3218 -19.4% 2595 proc-vmstat.thp_split_page
> 12163 ± 7% -22.1% 9473 ± 12% proc-vmstat.thp_split_pmd
> 8193516 +3.2% 8459146 proc-vmstat.unevictable_pgs_scanned
> 79085 ± 10% -7.8% 72890 interrupts.CAL:Function_call_interrupts
> 1139 ± 9% -10.7% 1018 ± 3% interrupts.CPU0.CAL:Function_call_interrupts
> 3596 ± 3% -13.8% 3100 ± 8% interrupts.CPU20.TLB:TLB_shootdowns
> 3602 ± 4% -12.6% 3149 ± 10% interrupts.CPU23.TLB:TLB_shootdowns
> 3512 ± 5% -9.9% 3163 ± 9% interrupts.CPU25.TLB:TLB_shootdowns
> 3512 ± 3% -12.1% 3088 ± 9% interrupts.CPU26.TLB:TLB_shootdowns
> 3610 ± 5% -13.2% 3134 ± 5% interrupts.CPU29.TLB:TLB_shootdowns
> 3602 ± 5% -17.4% 2973 ± 8% interrupts.CPU31.TLB:TLB_shootdowns
> 3548 ± 4% -12.7% 3098 ± 6% interrupts.CPU32.TLB:TLB_shootdowns
> 3637 ± 5% -15.2% 3085 ± 7% interrupts.CPU35.TLB:TLB_shootdowns
> 3588 ± 3% -12.7% 3131 ± 9% interrupts.CPU56.TLB:TLB_shootdowns
> 3664 ± 5% -14.3% 3142 ± 10% interrupts.CPU59.TLB:TLB_shootdowns
> 3542 ± 6% -13.0% 3082 ± 5% interrupts.CPU64.TLB:TLB_shootdowns
> 3539 ± 5% +12.4% 3977 ± 11% interrupts.CPU7.TLB:TLB_shootdowns
> 3485 ± 5% -13.0% 3033 ± 10% interrupts.CPU70.TLB:TLB_shootdowns
> 3651 ± 4% -16.1% 3062 ± 9% interrupts.CPU71.TLB:TLB_shootdowns
> 1.557e+10 ± 2% -8.1% 1.431e+10 ± 3% perf-stat.i.branch-instructions
> 1.887e+08 ± 9% -21.4% 1.484e+08 perf-stat.i.cache-misses
> 5.026e+08 ± 2% -8.6% 4.595e+08 ± 4% perf-stat.i.cache-references
> 2609 ± 3% +6.0% 2766 perf-stat.i.cycles-between-cache-misses
> 7.344e+09 -6.6% 6.861e+09 ± 3% perf-stat.i.dTLB-stores
> 6.969e+10 -7.6% 6.44e+10 ± 3% perf-stat.i.instructions
> 0.37 ± 2% -7.2% 0.34 perf-stat.i.ipc
> 43.29 ± 5% +3.7 46.94 ± 4% perf-stat.i.node-load-miss-rate%
> 15474576 ± 8% -23.9% 11782653 ± 13% perf-stat.i.node-load-misses
> 28.50 ± 6% +3.2 31.74 ± 3% perf-stat.i.node-store-miss-rate%
> 26447212 ± 5% -11.6% 23382361 ± 4% perf-stat.i.node-stores
> 0.61 +0.0 0.65 perf-stat.overall.branch-miss-rate%
> 37.58 ± 8% -5.2 32.39 ± 4% perf-stat.overall.cache-miss-rate%
> 2.91 ± 2% +3.4% 3.00 perf-stat.overall.cpi
> 1091 ± 10% +19.5% 1303 ± 3% perf-stat.overall.cycles-between-cache-misses
> 0.17 +0.0 0.18 ± 3% perf-stat.overall.dTLB-store-miss-rate%
> 5922 -6.6% 5533 ± 2% perf-stat.overall.instructions-per-iTLB-miss
> 0.34 ± 2% -3.3% 0.33 perf-stat.overall.ipc
> 1.462e+10 ± 2% -5.3% 1.384e+10 ± 3% perf-stat.ps.branch-instructions
> 1.765e+08 ± 10% -18.7% 1.435e+08 perf-stat.ps.cache-misses
> 6.926e+09 -4.0% 6.648e+09 ± 3% perf-stat.ps.dTLB-stores
> 6.555e+10 -5.0% 6.229e+10 ± 3% perf-stat.ps.instructions
> 14736035 ± 8% -21.6% 11547658 ± 14% perf-stat.ps.node-load-misses
> 2.703e+12 -4.4% 2.585e+12 ± 2% perf-stat.total.instructions
>
>
>
> stress-ng.madvise.ops
>
> 7000 +-+------------------------------------------------------------------+
> 6800 +-+ + |
> | : |
> 6600 +-+.+ ++.+ +.+ ++ + ++. : :+.+ +. ++ .++ +. ++ + +. + |
> 6400 +-+ ++ ++ + +.+ + ++ + ++ + : + ++ + ++.+ + ++ :+.++|
> | + + |
> 6200 +-+ |
> 6000 +-+ |
> 5800 +-+ |
> | |
> 5600 +-+ |
> 5400 +-+ |
> OO OOO O O O O O O O O O O |
> 5200 +-O O O OO OO OO O OOO O OO O O OOOO O O |
> 5000 +-+------------------------------------------------------------------+
>
>
> stress-ng.madvise.ops_per_sec
>
> 7000 +-+------------------------------------------------------------------+
> 6800 +-+ + |
> | : |
> 6600 +-+ : : |
> 6400 +-+.+++++.++++.+++++.+++++.++ ++.++++.+ +++.+++++.+++++.++++.++ ++.++|
> | + + |
> 6200 +-+ |
> 6000 +-+ |
> 5800 +-+ |
> | |
> 5600 +-+ |
> 5400 +-+ |
> |O O O O O O |
> 5200 O-O O OOO O OO OO OOOOO OOOOO OOOO OO O O O |
> 5000 +-+---------O---------------------------OO---------------------------+
>
>
> [*] bisect-good sample
> [O] bisect-bad sample
>
>
>
> Disclaimer:
> Results have been estimated based on internal Intel analysis and are provided
> for informational purposes only. Any difference in system hardware or software
> design or configuration may affect actual performance.
>
>
> Thanks,
> Rong Chen
>

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