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Mon, 16 Jun 2025 14:32:01 -0700 (PDT) From: Joshua Hahn To: SeongJae Park Cc: Andrew Morton , David Hildenbrand , Honggyu Kim , Johannes Weiner , Lorenzo Stoakes , Michal Hocko , Qi Zheng , Shakeel Butt , damon@lists.linux.dev, kernel-team@meta.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 0/3] mm/damon: use alloc_migrate_target() for DAMOS_MIGRATE_{HOT,COLD} Date: Mon, 16 Jun 2025 14:31:58 -0700 Message-ID: <20250616213159.2839382-1-joshua.hahnjy@gmail.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250616172346.67659-1-sj@kernel.org> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 4D9758000D X-Stat-Signature: 89n4d7ymx8w4wpqnmcagrmd8dzm9h4dz X-Rspam-User: X-HE-Tag: 1750109523-138644 X-HE-Meta: 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 b2gaYuEt 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 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 Mon, 16 Jun 2025 10:23:43 -0700 SeongJae Park wrote: > DAMOS_MIGRATE_{HOT,COLD} implementation resembles that for demotion, and > hence the behavior is also similar to that. But, since those are not > only for demotion but general migrations, it would be better to match > with that for move_pages() system call. Make the implementation and the > behavior more similar to move_pages() by not setting migration fallback > nodes, and using alloc_migration_target() instead of > alloc_migrate_folio(). > > alloc_migrate_folio() was renamed from alloc_demote_folio() and been > non-static function, to let DAMOS_MIGRATE_{HOT,COLD} call it. As > alloc_migration_target() is called instead, the renaming and de-static > changes are no more required but could only make future code readers be > confused. Revert the changes, too. Hi SJ, I hope you are doing well! These changes all look good to me. And I agree that changing the behavior to mimic migration as opposed to demotion might be helpful in making opportunities for others to use DAMOS as a means to perform other related works (like [1]), without having to use a "demotion" mechanism for simply moving pages around. I do have one question: I'm curious what kinds of changes callers can expect. Would I be correct in understanding that this is mostly a semantic change (aside from no longer having a fallback nodemask)? Just want to make sure I have a correct understanding of your intent was. In the meantime, feel free to add the following to the series: Reviewed-by: Joshua Hahn Have a great day! Joshua [1] https://lore.kernel.org/all/20250612181330.31236-1-bijan311@gmail.com/ Sent using hkml (https://github.com/sjp38/hackermail)