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    SubjectRe: [PATCH 00/40] Memory allocation profiling
    On Mon, May 01, 2023 at 09:54:10AM -0700, Suren Baghdasaryan wrote:
    > Performance overhead:
    > To evaluate performance we implemented an in-kernel test executing
    > multiple get_free_page/free_page and kmalloc/kfree calls with allocation
    > sizes growing from 8 to 240 bytes with CPU frequency set to max and CPU
    > affinity set to a specific CPU to minimize the noise. Below is performance
    > comparison between the baseline kernel, profiling when enabled, profiling
    > when disabled (nomem_profiling=y) and (for comparison purposes) baseline
    > with CONFIG_MEMCG_KMEM enabled and allocations using __GFP_ACCOUNT:
    >
    > kmalloc pgalloc
    > Baseline (6.3-rc7) 9.200s 31.050s
    > profiling disabled 9.800 (+6.52%) 32.600 (+4.99%)
    > profiling enabled 12.500 (+35.87%) 39.010 (+25.60%)
    > memcg_kmem enabled 41.400 (+350.00%) 70.600 (+127.38%)

    Hm, this makes me think we have a regression with memcg_kmem in one of
    the recent releases. When I measured it a couple of years ago, the overhead
    was definitely within 100%.

    Do you understand what makes the your profiling drastically faster than kmem?

    Thanks!

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