On Wed, Jul 26, 2023 at 8:20 AM Johannes Weiner <hannes@xxxxxxxxxxx> wrote: > > On Tue, Jul 25, 2023 at 07:20:02PM -0700, Yosry Ahmed wrote: > > On Tue, Jul 25, 2023 at 7:15 PM Roman Gushchin <roman.gushchin@xxxxxxxxx> wrote: > > > > > > On Wed, Jul 26, 2023 at 12:29:04AM +0000, Yosry Ahmed wrote: > > > > Currently, memcg uses rstat to maintain hierarchical stats. Counters are > > > > maintained for hierarchical stats at each memcg. Rstat tracks which > > > > cgroups have updates on which cpus to keep those counters fresh on the > > > > read-side. > > > > > > > > For non-hierarchical stats, we do not maintain counters. Instead, the > > > global? > > > > Do you mean "we do not maintain global counters"? I think "global" is > > confusing, because it can be thought of as all cpus or as including > > the subtree (as opposed to local for non-hierarchical stats). > > "global" seems fine to me, I don't think it's ambiguous in the direct > comparison with per-cpu counts. > > Alternatively, rephrase the whole thing? Something like: > > "Non-hierarchical stats are currently not covered by rstat. Their > per-cpu counters are summed up on every read, which is expensive." Rephrasing sounds good to me. I will send a v3 with the correct commit log and collected Acks to make Andrew's life easier.
