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    SubjectRe: [PATCH v3 0/5] mm/memcg: Reduce kmemcache memory accounting overhead
    Date
    On 4/14/21 11:26 PM, Masayoshi Mizuma wrote:
    >
    > Hi Longman,
    >
    > Thank you for your patches.
    > I rerun the benchmark with your patches, it seems that the reduction
    > is small... The total duration of sendto() and recvfrom() system call
    > during the benchmark are as follows.
    >
    > - sendto
    > - v5.8 vanilla: 2576.056 msec (100%)
    > - v5.12-rc7 vanilla: 2988.911 msec (116%)
    > - v5.12-rc7 with your patches (1-5): 2984.307 msec (115%)
    >
    > - recvfrom
    > - v5.8 vanilla: 2113.156 msec (100%)
    > - v5.12-rc7 vanilla: 2305.810 msec (109%)
    > - v5.12-rc7 with your patches (1-5): 2287.351 msec (108%)
    >
    > kmem_cache_alloc()/kmem_cache_free() are called around 1,400,000 times during
    > the benchmark. I ran a loop in a kernel module as following. The duration
    > is reduced by your patches actually.
    >
    > ---
    > dummy_cache = KMEM_CACHE(dummy, SLAB_ACCOUNT);
    > for (i = 0; i < 1400000; i++) {
    > p = kmem_cache_alloc(dummy_cache, GFP_KERNEL);
    > kmem_cache_free(dummy_cache, p);
    > }
    > ---
    >
    > - v5.12-rc7 vanilla: 110 msec (100%)
    > - v5.12-rc7 with your patches (1-5): 85 msec (77%)
    >
    > It seems that the reduction is small for the benchmark though...
    > Anyway, I can see your patches reduce the overhead.
    > Please feel free to add:
    >
    > Tested-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
    >
    > Thanks!
    > Masa
    >
    Thanks for the testing.

    I was focusing on your kernel module benchmark in testing my patch. I
    will try out your pgbench benchmark to see if there can be other tuning
    that can be done.

    BTW, how many numa nodes does your test machine? I did my testing with a
    2-socket system. The vmstat caching part may be less effective on
    systems with more numa nodes. I will try to find a larger 4-socket
    systems for testing.

    Cheers,
    Longman

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