From nobody Sun Feb 8 05:26:56 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5F9282F1FE6; Sun, 26 Oct 2025 18:22:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761502946; cv=none; b=ScJc+rmWqD5Icpq+3Wn8JhmEqz3NquZsPS4EJlt5sBGwqzXHKdFLk9EPb3oLffMyhLrxzHc3uKn3qON4to5XrRpnp3F/fg09/OpvmVz4ziPMEEVYvPzP6T74fHJ7URA4HpDE4t+7IgjDUGbZTMMrCcxLp77OjSASUi8GDKBjCGg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761502946; c=relaxed/simple; bh=I1qOOem2KN/JkZ9BYY8eeWzyQQxWRZ7InKt4fNjdwKE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Gw8Q2ePs1BZnnNi9CUiVLpwGIVVC82ZQl4kmrsDBpyyuc2X7eHNP6c2GQ5RXwjugA6WZtSn3DhAgqjgRAzTTFEkJVd/RdBiM1Q63UEJD9XrsSVK1XFJTIhgAyeXJChTYwrKD5MEDNYDEFyRemIixnEu+StSWAaPI+WPLsyUutKg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Hz1orSbv; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Hz1orSbv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B6B4BC116C6; Sun, 26 Oct 2025 18:22:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761502946; bh=I1qOOem2KN/JkZ9BYY8eeWzyQQxWRZ7InKt4fNjdwKE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Hz1orSbvkBt07uCPY9LqB+5RZ4lOiEganPCCSlYwGKdf8CP5+J7XAkwN5Ov9Ow2aX k1Hp1eHEVwLCMHudHdZ8AZ9Y3xVPutNbeQ8aEDMz0QHP1MCQk+C9E9SplA4v2E/dhG KSc2I1kpRL2KEyL7ZyrUzL+SZAKWCRwYsWz1E7yGWqMJwdkTzGV3cbPe+oNqtMfeoK duJx7rjzR/20lz3rrdDelbelInYeuR72NwUwFemhjiPTKLZfPmKmQ9p9pnToJcz3iC MjbpydH0AkfLc0zE8FfYF33u2a7C6oJIl062xJ3rV3EUmagGbs8KbeE2CHGUI6LP3N 0yzbVz46qNZYg== From: SeongJae Park To: Andrew Morton Cc: SeongJae Park , "Liam R. 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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/ad= min-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. =20 DAMON_STAT calculates how long each byte of the memory was not accessed un= til -now (idle time), based on the current DAMON results snapshot. If DAMON fo= und a -region of access frequency (nr_accesses) larger than zero, every byte of t= he -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 expos= es -the percentiles of the idle time values via this read-only parameter. Rea= ding -the parameter returns 101 idle time values in milliseconds, separated by c= omma. +now (idle time), based on the current DAMON results snapshot. For regions +having access frequency (nr_accesses) larger than zero, how long the curre= nt +access frequency level was kept multiplied by ``-1`` becomes the idlee tim= e of +every byte of the region. If a region has zero access frequency (nr_acces= ses), +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. --=20 2.47.3