On Wed, Oct 04, 2023 at 02:36:19PM -0400, Johannes Weiner <hannes@xxxxxxxxxxx> wrote: > Yes, it's because of node resolution which event counters generally > don't have. Some of the refault events influence node-local reclaim > decisions, see mm/vmscan.c::snapshot_refaults(). > > There are a few other event counters in the stat array that people > thought would be useful to have split out in > /sys/devices/system/node/nodeN/vmstat to understand numa behavior > better. > > It's a bit messy. > > Some events would be useful to move to 'stats' for the numa awareness, > such as the allocator stats and reclaim activity. > > Some events would be useful to move to 'stats' for the numa awareness, > but don't have the zone resolution required by them, such as > kswapd/kcompactd wakeups. Thanks for the enlightenment. > Some events aren't numa specific, such as oom kills, drop_pagecache. These are oddballs indeed. As with the normalization patchset these are counted as PAGE_SIZE^W 1 error but they should rather be an infinite error (to warrant a flush). So my feedback to this series is: - patch 1/2 -- creating two classes of units is consequence of unclarity between state and events (as in event=Δstate/Δt) and resolution (global vs per-node), so the better approach would be to tidy this up, - patch 2/2 -- it could use the single unit class that exists, it'll bound the error of printed numbers afterall (and can be changed later depending on how it affects internal consumers). My 0.02€, Michal
Attachment:
signature.asc
Description: PGP signature
