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Mercier" Date: Tue, 30 Apr 2024 10:29:31 -0700 Message-ID: Subject: Re: [PATCH v3 1/8] memcg: reduce memory size of mem_cgroup_events_index To: Yosry Ahmed Cc: Shakeel Butt , Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , kernel-team@meta.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 9530D40021 X-Stat-Signature: corf1roxejtbc19znat7d7wa186yw6pj X-HE-Tag: 1714498185-202491 X-HE-Meta: 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 fgcu5fp1 VhZ2cvkhlZQ5svAqzRdph84Vsg+KMWBl5uR66YF5YFn4PqEvpMyAs2pefHZHKu8OLX1fB8Dk0jQJ1E99bZzBpAnXWgCo6vglzEiIeTeZWkyCVokJ9Ht0Td03NFTYwh2NPjR3w6YOmB60UMNlFwfL3QBnSLibpE+hPuStmNPG8FhLtdr+tz8oKcrBK8Eju1J26bq+FJKh110I05xAFNz2MIqzAqd+865rSdJ5PxziqNVrUXn+xduQePAjMdpPoJgQiMqqxZc8eHfmnSA3AmofGoFTi5oH5dbfvfKvHIjMhBiWqvXBBcCU682rX4rjoARg0eSuTm9i1PfouTdI= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000010, 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, Apr 30, 2024 at 1:34=E2=80=AFAM Yosry Ahmed = wrote: > > On Mon, Apr 29, 2024 at 11:06=E2=80=AFPM Shakeel Butt wrote: > > > > mem_cgroup_events_index is a translation table to get the right index o= f > > the memcg relevant entry for the general vm_event_item. At the moment, > > it is defined as integer array. However on a typical system the max > > entry of vm_event_item (NR_VM_EVENT_ITEMS) is 113, so we don't need to > > use int as storage type of the array. For now just use int8_t as type > > and add a BUILD_BUG_ON() and will switch to short once NR_VM_EVENT_ITEM= S > > touches 127. > > > > Another benefit of this change is that the translation table fits in 2 > > cachelines while previously it would require 8 cachelines (assuming 64 > > bytes cachesline). > > > > Signed-off-by: Shakeel Butt > > Reviewed-by: Roman Gushchin > > Reviewed-by: Yosry Ahmed > Reviewed-by: T.J. Mercier