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b=YCPcERYvQkcQ7m6OKqSUY5DTahcgVHnZj5Wu21LbySTpf/HGgKguvEpe+UxexaNV6 huMHYEAVWTdAaGBJ8gXRO3VfSA3IsTGdwE22SpJCNYrdqt0TQsgJiSdLjvuJUvfqmw q2E11V6jLVEemLPo64N1sEE+K0L3W842PgS8TIqDMP7gssBIuQVAzXqhFtkB2LgSuA pF0lemEq/lUbBL4b2J2XQxr3jlmoA5SdliEzyeToqlzttdSUYFOK7AEVWh5d8KrV8V Sr7RJv+2dGPFLHFH0zPi+LHsL06Y4+R193x+APbk9avb7ZRdLN33wLyjCNNpfkQtR5 nfvxtPFskPMyg== From: SeongJae Park To: SeongJae Park Cc: Andrew Morton , damon@lists.linux.dev, kernel-team@meta.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH 0/2] mm/damon/stat: expose auto-tuned intervals and non-idle ages Date: Thu, 11 Sep 2025 19:06:19 -0700 Message-Id: <20250912020619.59642-1-sj@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250910040022.168223-1-sj@kernel.org> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: D8201A0012 X-Stat-Signature: q7kk6j8ufck9r8xdnc4i6gzta9behwtq X-Rspam-User: X-HE-Tag: 1757642784-561683 X-HE-Meta: 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 KQaQlrdy Pw767HfcBcxu6y2Hl/DFxeavavvQOrM0Ox1arGeAq2/vTWvBF2vW8Iguke7R7AC+5DQ+XDN1Z5VhtJvqgk5wE7Yb5L2kXrrBuyYlCO7jY5t1Hy1Uta4ZhKQyYsue8NaiGcaU+qAqwFKgSh1BBt2jOOtQO4hosZnjQkRl1FG08aJFW6q1PZkLWno1/T4s4eA4Ex3dN/2cWIclGdry4h67zIFAYoRrMa/cdvMs7 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 Tue, 9 Sep 2025 21:00:20 -0700 SeongJae Park wrote: > DAMON_STAT is intentionally providing limited information for easy > consumption. From production fleet level usages, below limitations are > found, though. > > The aggregation interval of DAMON_STAT represents the granularity of the > memory_idle_ms_percentiles. But it is auto-tuned and not exposed to > users, so users cannot know the granularity. > > All memory regions of non-zero (positive) nr_accesses are treated as > having zero idle time. A significant portion of production systems have > such zero idle time. Hence breakdown of warm and hot data is > impossible. > > To overcome the limitations, expose the auto-tuned aggregation interval > with a new parameter named xxx and the age of non-zero nr_accesses s/xx/aggr_interval_us/ Forgot updating that before posting, sorry. The next version should fix it. Thanks, SJ [...]