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b=tXhhZoDh1xlzRdtNioCo5fcVnBOKPPHc+KSgUrYbO3t0sBRMiC4MB2a8Ri3/h4IPJ ke6jfsPtz+uLa0gJqTpRFHXy7aij0dZlbfeRf/fYknU30A919f385bz9Y+ZPVX162z AQXFlIK7lpJb8BVAthQN7HKrA00jK3/wvGLps3dboqg1v/BiVVrE0wCqYjVXlIXc9J GctHQ8JQu9LqET0oUeFuLFwjlVz7eKQz3DnecDARvsFU6XmQi2LYq9ZYVSR4EWmnIW 6qhOkLDpoqE7Nyzfh2qeUcO+exHZdP24vNi2CGFUCRpS33eXU/s/FEzyov5wHwrFQ3 ch3zAp7q5MrLw== From: SeongJae Park To: Josh Law Cc: SeongJae Park , akpm@linux-foundation.org, damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 0/2] mm/damon/core: Performance optimizations for the kdamond hot path Date: Mon, 23 Mar 2026 07:06:24 -0700 Message-ID: <20260323140625.79976-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260322214325.260007-1-objecting@objecting.org> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: nqu7q7w76xhw7hgfg17q19ouc5wdfu17 X-Rspamd-Server: rspam09 X-Rspam-User: X-Rspamd-Queue-Id: 510BF40002 X-HE-Tag: 1774274794-419204 X-HE-Meta: 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, 22 Mar 2026 21:43:23 +0000 Josh Law wrote: > Hello, > > This patch series provides two performance optimizations for the DAMON > core, specifically targeting the hot paths in kdamond. > > The first patch optimizes kdamond_apply_schemes() by inverting the loop > order. By iterating over schemes first and regions second, we can > evaluate scheme-level invariants (like activation status and quotas) > once per scheme rather than for every single region. This significantly > reduces CPU overhead when multiple schemes are present or when quotas > are reached. > > The second patch eliminates a hardware integer division in > damon_max_nr_accesses() by using the pre-cached aggr_samples value. > Since this function is called once per region per sampling interval, > removing the division provides a measurable reduction in CPU cycles > spent in the access rate update path. > > Changes from v2: > - Fix multi-line if statement alignment in the first patch to satisfy > checkpatch --strict. > > Changes from v1: > - Use min_t(unsigned long, ...) in damon_max_nr_accesses() to satisfy > checkpatch warnings and improve readability. Thank you for adding the change log. Please also consider adding links [1] to previous versions. Also, please consider giving at least about one day before sending new revision of a series, so that people can get a chance to review. If you find something that you need to change on new version, you can comment first about your planned change, and wait for others' comments. [1] https://docs.kernel.org/process/submitting-patches.html#commentary Thanks, SJ [...]