From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 C580347ECDC; Mon, 14 Sep 2026 14:20:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789395611; cv=none; b=X8VXVRauwyLeSg4M6bitMH8W/RvEU/p1Fgx2XElhmcBJ2aJSBwqEqvHBwVe2JaaE2Z+Jq0Wyg/T98Vm5F1BFkDSG2xj0IbJQ8QIeUJzJh14apuz34YEjo+lNgleWrBkynoHrd59PKiMpiX4gIKzhfqfZG74qmjzpll4XJy+Tv3Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789395611; c=relaxed/simple; bh=oWpASUYUf1MQMHW4bMHsGYFavW7vYaxsR0F3qU5hKqo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QsZl9xziwKFm3WiSC2Tnzu1PXU+pSdq6SaIo8xo7iVFT5+410ci0KB+LptDz8VMTUGSEX/5uKNvrFBCk+w3ntRjhx4uYf3QZqaOBnV5nJT8g0meGYtvkM13C/9ox/tgTllFurGp7yL8D+CCIxCwrJv6s5EW3wck0hMpvtFrqES8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LLAJKd3P; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LLAJKd3P" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DAA581F0089C; Mon, 14 Sep 2026 14:20:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789395603; bh=dgI5/uHVhGU/u/lFuomzDRYuBHWw9s688+WF+gpTSJY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=LLAJKd3PZfZJLA2mghR2o10iU2ZFbouGRqCNO/Ce//Yu5KWtT1Fb38VyB0L08FCuA ncSquZ0pmtNWj09L9+9wH2JgvSpzPbs7SgODgo6YgH3GSKvF/qjQlYeTePa6G5siUg Bdkg6gHk7rP4yAUkljf3cR/u0FwM7Cj2fwmJgMDjiFuBju+cdwiJREDEMEH9yQgYbO ET0CLVkg/JmOcmT9J9rFgy34S3fSuxjIQ0YUeeiTvpQJ9720JaTYJ+mHvdGA6WdHWp 90jegwteY51FeTim7QjFIXDEhCh7EoyJQSAdw/7FXomE+LQsrBn3qMa+PV60IZjwTR 9hmHyPPPeai3g== From: SJ Park To: Andrew Morton Cc: Liew Rui Yan , "Liam R. Howlett" , David Hildenbrand , Jonathan Corbet , Lorenzo Stoakes , Michal Hocko , Mike Rapoport , Randy Dunlap , SJ Park , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , damon@lists.linux.dev, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 5/6] Docs/mm/damon/design: clarify when qt_exceeds increases Date: Mon, 14 Sep 2026 07:19:50 -0700 Message-ID: <20260914141952.91465-6-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260914141952.91465-1-sj@kernel.org> References: <20260914141952.91465-1-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: 8bit From: Liew Rui Yan qt_exceeds counts how many times a scheme's quota has been exceeded. When using the temporal auto-tuning algorithm, the effective size quota becomes zero once the goal is [over-]achieved. In this case, the quotas are still set, so qt_exceeds keeps increasing once per quota reset interval while the goal stays achieved. Clarify this behavior in the design document. Signed-off-by: Liew Rui Yan Reviewed-by: SJ Park Signed-off-by: SJ Park --- Changes from v1 - v1: https://lore.kernel.org/20260910112255.157012-1-aethernet65535@gmail.com - Collect R-b: From SJ. - Rebase to latest mm-new. Changes from RFC v1 - RFC v1: https://lore.kernel.org/damon/20260908175105.42558-2-aethernet65535@gmail.com - Simplify the explanation. Do not provide a complete definition of qt_exceeds, but rather explain only the increment condition when using temporal auto-tuning algorithm, simply to prevent users from becoming confused and being unable to find any explanation. Documentation/mm/damon/design.rst | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst index cb116a82ff20b..ad09416dfb21a 100644 --- a/Documentation/mm/damon/design.rst +++ b/Documentation/mm/damon/design.rst @@ -696,7 +696,9 @@ There are two such tuning algorithms that users can select as they need. fast as possible, using maximum allowed quota, but only for a temporal short time. When the quota is under-achieved, this algorithm keeps tuning quota to a maximum allowed one. Once the quota is [over]-achieved, this sets the - quota zero. Useful for deterministic control required environments. + quota zero. Useful for deterministic control required environments. Note + that the zero quota is a valid quota, and therefore ``qt_exceeds`` :ref:`stat + ` will keep increasing in this case. The goal can be specified with five parameters, namely ``target_metric``, ``target_value``, ``current_value``, ``nid`` and ``path``. The auto-tuning -- 2.47.3