Hello. On Mon, Aug 21, 2023 at 08:54:55PM +0000, Yosry Ahmed <yosryahmed@xxxxxxxxxx> wrote: > For userspace reads, unified flushing leads to non-deterministic stats > staleness and reading cost. I only skimed previous threads but I don't remember if it was resolved: a) periodic flushing was too much spaced for user space readers (i.e. 2s delay is too much [1]), b) periodic flushing didn't catch up (i.e. full tree flush can occassionaly take more than 2s) leading to extra staleness? [1] Assuming that nr_cpus*MEMCG_CHARGE_BATCH error bound is also too much for userspace readers, correct? > The cost of userspace reads are now determinstic, and depend on the > size of the subtree being read. This should fix both the *sometimes* > expensive reads (due to flushing the entire tree) and occasional > staless (due to skipping flushing). This is nice, thanks to the atomic removal in the commit 0a2dc6ac3329 ("cgroup: remove cgroup_rstat_flush_atomic()"). I think the smaller chunks with yielding could be universally better (last words :-). Thanks, Michal
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