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Mon, 27 Jul 2026 10:23:59 -0700 (PDT) Date: Mon, 27 Jul 2026 13:23:55 -0400 From: Johannes Weiner To: Usama Arif Cc: Andrew Morton , david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, kasong@tencent.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, chrisl@kernel.org, nphamcs@gmail.com, baoquan.he@linux.dev, youngjun.park@lge.com, roman.gushchin@linux.dev, muchun.song@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, rientjes@google.com, kernel-team@meta.com Subject: Re: [PATCH v5 2/3] mm/vmscan: add pgrotate_anon and pgrotate_file vmstat counters Message-ID: References: <20260727162550.2032-1-usama.arif@linux.dev> <20260727162550.2032-3-usama.arif@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260727162550.2032-3-usama.arif@linux.dev> X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: A85E1180007 X-Stat-Signature: y159953fxya6znu41oq8pard3kwu9kg7 X-HE-Tag: 1785173040-371455 X-HE-Meta: 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 WmFakJgG 7R29mpl/yGaNOznQiMRLZmH5VuUGLP4wwHZybGrkt2SbzvYXC70Okw08AFtsMaIjHerFP34+wb5auUUPGMapkuN8NnpUbc3CPSAeZ7pVzJ0AiXOrl8PiwJOvJfPqhGzNiibTtzfjfL+ySbg3XdSMGlKUhHm9qJQNch/ZFH3H2MPd5UIchpCbRQwPLIvwTYbgxPeHT5n8h8ApiH0mNy5EHnMyOFuQsrrbe+w/cZoxwMByreHhTvM/bCEgnu8HSfNs4isSTLSanicjC5L9cnXyYLe7FXRUo9oaiMU8biBEYiqBm9z8Q0W6ptF9WW+saGGiz/7bI2xIhilWlT4qKrg9+htn9pxxEkEHLumkWB+dSYhQXncXKdpYKNl+vkvdMM6jcK+tNvFJjnWsTsq8Xm7fY6DsIwijF6viGxNt35swlnIwP15ptvmSFxgL/UJi52BH8a07bPFMeP3Tlt+pwtlG0T+p5bQljj4hlAHGo Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jul 27, 2026 at 09:23:24AM -0700, Usama Arif wrote: > Reclaim can spend substantial work on an LRU type without immediately > reclaiming or demoting a corresponding amount of memory. Record this > work in PGROTATE_ANON and PGROTATE_FILE. > > For classic LRU reclaim: > > - Inactive-list reclaim adds nr_scanned - nr_reclaimed to the > corresponding anon/file counter when isolation succeeds. > - Active-list reclaim adds referenced executable file folios that > are retained on the active list to PGROTATE_FILE. Active anon > reclaim does not contribute this component. > > For MGLRU, add the number of initially isolated pages that remain > unreclaimed after both the initial and retry passes to the counter for > the selected anon/file type. > > These counters are distinct from the existing pgrotated vm event. > pgrotated records an actual move to the inactive-list tail, primarily > after reclaim-marked writeback completes or failed invalidation leaves > a folio for accelerated reclaim. PGROTATE_ANON and PGROTATE_FILE > measure reclaim cost and do not imply that a folio moved to an LRU tail. > > A subsequent patch will consume these counters for anon/file scan > balancing. > > Signed-off-by: Usama Arif Acked-by: Johannes Weiner