Messages in this thread | | | Date | Wed, 6 Jan 2021 03:43:36 +0000 | From | Chris Down <> | Subject | Re: [PATCH 2/2] mm: memcg: add a new MEMCG_UPDATE_BATCH |
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Feng Tang writes: >One further thought is, there are quite some "BATCH" number in >kernel for perf-cpu/global data updating, maybe we can add a >global flag 'sysctl_need_accurate_stats' for > if (sysctl_need_accurate_stats) > batch = SMALLER_BATCH > else > batch = BIGGER_BATCH
Moving decisions like this to the system administrator is not really a solution to the problem -- inclusion should at least be contingent on either having "correct-ish" stats exported to userspace. Displaying broken stats to the user -- even with a configuration knob -- is less than ideal and is likely to confuse and confound issues in future.
I would also like to see numbers from more real-world workloads. MEMCG_CHARGE_BATCH is certainly fairly arbitrary as-is, but if it is going to be changed, the reason for that change and its implications (positive and negative) for real-world workloads must be well understood, and I'm not sure we're there yet.
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