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Mercier" Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , Efly Young , android-mm@google.com, yuzhao@google.com, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: memcg: Use larger chunks for proactive reclaim Message-ID: References: <20240131162442.3487473-1-tjmercier@google.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="lz6s2q5edho5n2za" Content-Disposition: inline In-Reply-To: <20240131162442.3487473-1-tjmercier@google.com> X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 2DC68100022 X-Stat-Signature: ds1wniapkc7rfyxtfprxgnko3bk45j5i X-HE-Tag: 1706795844-824769 X-HE-Meta: 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 1RkXwG2V 9tAjukkQHLykR/zAQrZuyfwGxuyQd3K//XUrH/4tSVMx+DZ63iLm8cqpwK7JdnjYfPuAJKmgGwF+8LADarbvimERHJu6VztSFX2pU0gYn7q2Q6cGsOEnzMO3crWfO3shj+VreBOvaFJPM1C82LNCAfgSkljFsCQrRIJxJTf+FXFw1rYyVRIDXOHu3FD9wjKXz3A4dOHAc06siKGZ+KUSuYEZF4RJQXtrS/lgmVib4Z1zlN9gAIl5BwTlRmICw1CKqZGd5ogIyU2tFlC9u1QhaVZATu2MUyhg142cbDRZqY5OSu6c= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000048, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: --lz6s2q5edho5n2za Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hello. On Wed, Jan 31, 2024 at 04:24:41PM +0000, "T.J. Mercier" wrote: > reclaimed =3D try_to_free_mem_cgroup_pages(memcg, > - min(nr_to_reclaim - nr_reclaimed, SWAP_CLUSTER_MAX), > + max((nr_to_reclaim - nr_reclaimed) / 4, > + (nr_to_reclaim - nr_reclaimed) % 4), The 1/4 factor looks like magic.=20 Commit 0388536ac291 says: | In theory, the amount of reclaimed would be in [request, 2 * request). Doesn't this suggest 1/2 as a better option? (I didn't pursue the theory.) Also IMO importantly, when nr_to_reclaim - nr_reclaimed is less than 8, the formula gives arbitrary (unrelated to delta's magnitude) values. Regards, Michal --lz6s2q5edho5n2za Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQQpEWyjXuwGT2dDBqAGvrMr/1gcjgUCZbujQAAKCRAGvrMr/1gc jiEnAQCQGBITdwktnX+PB1XMOwtBDaDA8QEg/Imo7oFBWH8AMwEAsK96LQZSYVCP vXmosthBsfuwtAklzkEeE5PYQsmvKgw= =hhY/ -----END PGP SIGNATURE----- --lz6s2q5edho5n2za--