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Howlett" , David Hildenbrand , Jonathan Corbet , Lorenzo Stoakes , Michal Hocko , Mike Rapoport , Suren Baghdasaryan , Vlastimil Babka , damon@lists.linux.dev, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 8/8] Docs/admin-guide/mm/damon/stat: document negative idle time Date: Sun, 26 Oct 2025 11:22:13 -0700 Message-ID: <20251026182216.118200-9-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20251026182216.118200-1-sj@kernel.org> References: <20251026182216.118200-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 307484000C X-Stat-Signature: 7c1g1t3af5zx6po7ehzimytxxqe8c7uc X-HE-Tag: 1761502946-764387 X-HE-Meta: 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 Y/4EkZ+I u7G8X5xc2fNYxot1hLwquJWqVSyUWo/0eqBr/O8ldoKRXdI4CEp1C7aqJQr9sBrqBFmPu4+vJiODQax02pnTHfVerCqYhlZcB2q89vzOeOpb6XG3NrBeozPyyAGvsItiZj9FNWSGcM8HNursJ3aRIcPIDgU+oCbfgh8DkvacDrfunh4mAxtHk8GIwOY7VJeLOPSXlXWmrXhCe9u0hywYU43jYZcHVFYuVyhQ4lTdEvOq5pTU= 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: Commit a983a26d5298 ("mm/damon/stat: expose negative idle time") introduced the negative idle time feature for DAMON_STAT. But it is not documented. Document it on the usage document. Signed-off-by: SeongJae Park --- Documentation/admin-guide/mm/damon/stat.rst | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/Documentation/admin-guide/mm/damon/stat.rst b/Documentation/admin-guide/mm/damon/stat.rst index 754f98d47617..e5a5a2c4f803 100644 --- a/Documentation/admin-guide/mm/damon/stat.rst +++ b/Documentation/admin-guide/mm/damon/stat.rst @@ -74,12 +74,13 @@ memory_idle_ms_percentiles Per-byte idle time (milliseconds) percentiles of the system. DAMON_STAT calculates how long each byte of the memory was not accessed until -now (idle time), based on the current DAMON results snapshot. If DAMON found a -region of access frequency (nr_accesses) larger than zero, every byte of the -region gets zero idle time. If a region has zero access frequency -(nr_accesses), how long the region was keeping the zero access frequency (age) -becomes the idle time of every byte of the region. Then, DAMON_STAT exposes -the percentiles of the idle time values via this read-only parameter. Reading -the parameter returns 101 idle time values in milliseconds, separated by comma. +now (idle time), based on the current DAMON results snapshot. For regions +having access frequency (nr_accesses) larger than zero, how long the current +access frequency level was kept multiplied by ``-1`` becomes the idlee time of +every byte of the region. If a region has zero access frequency (nr_accesses), +how long the region was keeping the zero access frequency (age) becomes the +idle time of every byte of the region. Then, DAMON_STAT exposes the +percentiles of the idle time values via this read-only parameter. Reading the +parameter returns 101 idle time values in milliseconds, separated by comma. Each value represents 0-th, 1st, 2nd, 3rd, ..., 99th and 100th percentile idle times. -- 2.47.3