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Mercier" Cc: Johannes Weiner , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , Efly Young , android-mm@google.com, yuzhao@google.com, mkoutny@suse.com, Yosry Ahmed , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] mm: memcg: Use larger batches for proactive reclaim Message-ID: References: <20240202233855.1236422-1-tjmercier@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Queue-Id: EACFC40006 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: cjyrd89s8a6piq8qq4timccswbzw3y9i X-HE-Tag: 1708344692-237178 X-HE-Meta: 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 h4pPtMq+ GjHPl15uOQedmkW4k1bbrVfcR+fD9mzj/pciI7zhdYgS6PHuZltfcdgzEuNdIcN6Vj4GLzWLW95hy33sxN3Mid6Ga1bLepHPf8yiT9PdgdgiiGff3kRu+jwYdo4V3xfp5NDFoU0WEiogTufTkCMHDDCD1g2YwPppubtVQw/E+6i568aabc+PYPRdV3l4LIyT62cdLv+41wnZZw0LArjpfRNZATPMtQLixykKpMfSwAMqnqR/cstpgSuQ2Zl6xZx799i9DqzFblpxmePVxvmiK2YU7bLpr7XkYEAiWBxlkCngfqXU= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, 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 Tue 06-02-24 09:58:41, Michal Hocko wrote: > On Mon 05-02-24 20:01:40, T.J. Mercier wrote: > > On Mon, Feb 5, 2024 at 1:16 PM Michal Hocko wrote: > > > > > > On Mon 05-02-24 12:47:47, T.J. Mercier wrote: > > > > On Mon, Feb 5, 2024 at 12:36 PM Michal Hocko wrote: > > > [...] > > > > > This of something like > > > > > timeout $TIMEOUT echo $TARGET > $MEMCG_PATH/memory.reclaim > > > > > where timeout acts as a stop gap if the reclaim cannot finish in > > > > > TIMEOUT. > > > > > > > > Yeah I get the desired behavior, but using sc->nr_reclaimed to achieve > > > > it is what's bothering me. > > > > > > I am not really happy about this subtlety. If we have a better way then > > > let's do it. Better in its own patch, though. > > > > > > > It's already wired up that way though, so if you want to make this > > > > change now then I can try to test for the difference using really > > > > large reclaim targets. > > > > > > Yes, please. If you want it a separate patch then no objection from me > > > of course. If you do no like the nr_to_reclaim bailout then maybe we can > > > go with a simple break out flag in scan_control. > > > > > > Thanks! > > > > It's a bit difficult to test under the too_many_isolated check, so I > > moved the fatal_signal_pending check outside and tried with that. > > Performing full reclaim on the /uid_0 cgroup with a 250ms delay before > > SIGKILL, I got an average of 16ms better latency with > > sc->nr_to_reclaim across 20 runs ignoring one 1s outlier with > > SWAP_CLUSTER_MAX. > > This will obviously scale with the number of memcgs in the hierarchy but > you are right that too_many_isolated makes the whole fatal_signal_pending > check rather inefficient. I haven't missed that. The reclaim path is > rather convoluted so this will likely be more complex than I > anticipated. I will think about that some more. > > In order to not delay your patch, please repost with suggested updates > to the changelog. This needs addressing IMO but I do not think this is > critical at this stage. Has there been a new version or a proposal to refine the changelog posted? -- Michal Hocko SUSE Labs