On Mon, Jun 24, 2024 at 03:21:22PM GMT, Yosry Ahmed wrote: > On Mon, Jun 24, 2024 at 3:17 PM Shakeel Butt <shakeel.butt@xxxxxxxxx> wrote: > > > > On Mon, Jun 24, 2024 at 02:43:02PM GMT, Yosry Ahmed wrote: > > [...] > > > > > > > > > There is also > > > > > a heuristic in zswap that may writeback more (or less) pages that it > > > > > should to the swap device if the stats are significantly stale. > > > > > > > > > > > > > Is this the ratio of MEMCG_ZSWAP_B and MEMCG_ZSWAPPED in > > > > zswap_shrinker_count()? There is already a target memcg flush in that > > > > function and I don't expect root memcg flush from there. > > > > > > I was thinking of the generic approach I suggested, where we can avoid > > > contending on the lock if the cgroup is a descendant of the cgroup > > > being flushed, regardless of whether or not it's the root memcg. I > > > think this would be more beneficial than just focusing on root > > > flushes. > > > > Yes I agree with this but what about skipping the flush in this case? > > Are you ok with that? > > Sorry if I am confused, but IIUC this patch affects all root flushes, > even for userspace reads, right? In this case I think it's not okay to > skip the flush without waiting for the ongoing flush. So, we differentiate between userspace and in-kernel users. For userspace, we should not skip flush and for in-kernel users, we can skip if flushing memcg is the ancestor of the given memcg. Is that what you are saying?
