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b=E291hYDDt266iKId2+/0Ulc+8XlwYwBRK/bWLoreluA1QtuEg1IIO/3JIO33FAD10 LjzMB2Hv+QRFiD4ZVQDLXUVc+zUmgZwBSUgDTupD7LPdpcW65lcLWQ3nZF45ULPsUK DQOkexmAF21ViEpHQsQJbSlzsooB45EUH6gTEpPuuIUDtvzqp3HKJHfV8qbmpGoo7c U6aSfq1bdHwEm0n5h9YSd9/C5Z2L7gkw69h3PDpHUJMIVdBoUDMylDxqScVijCymhF R7MPuPl8vdbOLQFActr16eomNhWUND5Vd/Yr01kG15wKHY+5iaFubYFCmSdJPpYS3F OcxooJXU1nZiw== From: SeongJae Park To: Vinay Banakar Cc: SeongJae Park , Bharata B Rao , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, willy@infradead.org, mgorman@suse.de, Wei Xu , Greg Thelen Subject: Re: [PATCH] mm: Optimize TLB flushes during page reclaim Date: Thu, 23 Jan 2025 09:23:38 -0800 Message-Id: <20250123172338.53472-1-sj@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 080EE20007 X-Stat-Signature: 4kk331gad8i5tfi1juzeoc58i385y7xp X-Rspam-User: X-HE-Tag: 1737653022-228833 X-HE-Meta: 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 XbMlyHi8 h2RWsy4C9+v6kinOXWPxm/D1Fe8WQnA52bMAaiIevV6h6FxRuamnTggJbwE8W+G/VnBgA6IpmGUiGVykIm8UbeE+3FbI5homCRrVRxwaG4IiUADMw52cpRbA7nSItLponUuIpmJHLGWqR0/YF4YS1mRUmy2RbufnIU/CKYB8pzjn3Wm05Agm7caWKfDovV95akWpCWeq+TNKVX62x9r9um/HqpUIfpW9v8nR7iUBgMbFRvskpDrHZNVH5vqw48KV14fAO X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, 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 Thu, 23 Jan 2025 11:11:13 -0600 Vinay Banakar wrote: > On Wed, Jan 22, 2025 at 2:05 PM SeongJae Park wrote: > > damon_pa_pageout() from mm/damon/paddr.c also calls shrink_folio_list() similar > > to madvise.c, but it doesn't aware such batching behavior. Have you checked > > that path? > > Thanks for catching this path. In damon_pa_pageout(), > shrink_folio_list() processes all pages from a single NUMA node that > were collected (filtered) from a single DAMON region (r->ar.start to > r->ar.end). This means it could be processing anywhere from 1 page up > to ULONG_MAX pages from a single node at once. Thank you Vinay. That's same to my understanding, except that it is not limited to a single NUMA node. A region can have any start and end physical addresses, so it could cover memory of different NUMA nodes. > With the patch, we'll > send a single IPI for TLB flush for the entire region, reducing IPIs > by a factor equal to the number of pages being reclaimed by DAMON at > once (decided by damon_reclaim_quota). I guess the fact that the pages could belong to differnt NUMA nodes doesn't make difference here? > > My only concern here would be the overhead of maintaining the > temporary pageout_list for batching. However, during BIO submission, > the patch checks if the folio was reactivated, so submitting to BIO in > bulk should be safe. > > Another option would be to modify shrink_folio_list() to force batch > flushes for up to N pages (512) at a time, rather than relying on > callers to do the batching via folio_list. Both sounds good to me :) Thanks, SJ > > Thanks! > Vinay