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From: Shakeel Butt To: Yosry Ahmed Cc: Jesper Dangaard Brouer , tj@kernel.org, cgroups@vger.kernel.org, hannes@cmpxchg.org, lizefan.x@bytedance.com, longman@redhat.com, kernel-team@cloudflare.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH V2] cgroup/rstat: Avoid thundering herd problem by kswapd across NUMA nodes Message-ID: References: <171923011608.1500238.3591002573732683639.stgit@firesoul> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 43E5D40004 X-Stat-Signature: jkw7rzwjmjujuei6arei1o7y5auyr35u X-HE-Tag: 1719267441-793185 X-HE-Meta: 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 2Mb1lSjy Bunwk6AwycF0tCz9mpnvwcssPMJ/sNHKcHJNShzo/N/cJIL5tux0INtpnrgO7pIb66RG5rZEQ4EHPxKDPypQSwQ9OdaOdfeWkLjqOI9hbZc/Vhzhnl2f5Dn1RY/RHpe52GoOUwBD7Qfvyq3V0ylPHn9CcTQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.064052, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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?