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    SubjectRe: [LKP] Re: [mm/memcg] bd0b230fe1: will-it-scale.per_process_ops -22.7% regression
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    On 11/2/2020 6:02 PM, Michal Hocko wrote:
    > On Mon 02-11-20 17:53:14, Rong Chen wrote:
    >>
    >>
    >> On 11/2/20 5:27 PM, Michal Hocko wrote:
    >>> On Mon 02-11-20 17:15:43, kernel test robot wrote:
    >>>> Greeting,
    >>>>
    >>>> FYI, we noticed a -22.7% regression of will-it-scale.per_process_ops due to commit:
    >>>>
    >>>>
    >>>> commit: bd0b230fe14554bfffbae54e19038716f96f5a41 ("mm/memcg: unify swap and memsw page counters")
    >>>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
    >>> I really fail to see how this can be anything else than a data structure
    >>> layout change. There is one counter less.
    >>>
    >>> btw. are cgroups configured at all? What would be the configuration?
    >>
    >> Hi Michal,
    >>
    >> We used the default configure of cgroups, not sure what configuration you
    >> want,
    >> could you give me more details? and here is the cgroup info of will-it-scale
    >> process:
    >>
    >> $ cat /proc/3042/cgroup
    >> 12:hugetlb:/
    >> 11:memory:/system.slice/lkp-bootstrap.service
    >
    > OK, this means that memory controler is enabled and in use. Btw. do you
    > get the original performance if you add one phony page_counter after the
    > union?
    >
    I add one phony page_counter after the union and re-test, the regression
    reduced to -1.2%. It looks like the regression caused by the data
    structure layout change.

    =========================================================================================
    tbox_group/testcase/rootfs/kconfig/compiler/nr_task/mode/test/cpufreq_governor/ucode/debug-setup:

    lkp-hsw-4ex1/will-it-scale/debian-10.4-x86_64-20200603.cgz/x86_64-rhel-8.3/gcc-9/50%/process/page_fault2/performance/0x16/test1

    commit:
    8d387a5f172f26ff8c76096d5876b881dec6b7ce
    bd0b230fe14554bfffbae54e19038716f96f5a41
    b3233916ab0a883e1117397e28b723bd0e4ac1eb (debug patch add one phony
    page_counter after the union)

    8d387a5f172f26ff bd0b230fe14554bfffbae54e190 b3233916ab0a883e1117397e28b
    ---------------- --------------------------- ---------------------------
    %stddev %change %stddev %change %stddev
    \ | \ | \
    187632 -22.8% 144931 -1.2% 185391
    will-it-scale.per_process_ops
    13509525 -22.8% 10435073 -1.2% 13348181
    will-it-scale.workload



    --
    Zhengjun Xing

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