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 8D715377A81; Sun, 4 Oct 2026 08:01:17 +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=1791100878; cv=none; b=cfMdt2nPfZq6p+c77kcPBuxIbKPSRs3FLxJecftwRC64CgJ/U8QuQUtO5BT9CXUJwqMk/m36/jiphgvSyhL8hpxw5FpTilPxzaXJZJLO4jCNt2XiZ0ZFoNZk5oKAp9Fsx7LeXnS7KaBv13Ul/kjQ//QP/Hgrxv0l+4Mvos3ppjo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791100878; c=relaxed/simple; bh=iTOH66FzZXboDlHhAvgDRCZs+Jh0LxFBQvkk2OT22XE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=AHoQHagvM5u6EdxxcA8bV+mJZROAFrnrzZ6IolvoWJpe0fj1kjBjihgaDJcK+ZabB/qvYBthqY3lOt5nFw/mReFWIkygyRTqIwxUHkdRTOXwGysU3WEpn9/Xpcrmb++Fv2wYW4NLkKekyVYXI+o891AOkUjJvGFbl2CNopWWHxQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bV2Oz3wP; 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="bV2Oz3wP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 02D391F000FF; Sun, 4 Oct 2026 08:01:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791100877; bh=p0bhkDeR0q/RIGHHdpd7D589iSN3oIrJp74cDlV3Lkg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=bV2Oz3wPh9CI2vgAGfVd43hYzt6c1uvlk7ix0Dq2MmknOdhfzHxfi/W7w31THvoWE ebDtjhVfvO+acPp+9yL7RsNOL5Rnl8eTDIO+Fe1PPIQN6rHL5hOhIDu6621+gzqlv8 H83jxW1Eh7YMuhBvyHR7p5n+lW2MQhJ5AQ04Ynrvyg6TVqawhuYYm2op2HCUbhR+H2 ADXlY4fPPr0KuKg2w4ISnUM2WB9WJk9Mi3a4P8GEh0YgdiHnq8lPBivxcQSSUJYM1z iVyyKP1HFEX+iRR952RqoePaLSF7/UVXRTOuVV/FT7PJh4eTrM7eD2LUyNM9bh8SmF xfMmHCv1XGaSg== From: SJ Park To: Ravi Jonnalagadda Cc: SJ Park , Andrew Morton , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Steven Rostedt , Masami Hiramatsu , Jonathan Corbet , Bijan Tabatabai , Ajay Joshi , Honggyu Kim , Yunjeong Mun , Akinobu Mita , Lian Wang , Kunwu Chan Subject: Re: [PATCH] mm/damon: add damos_node_eligible_mem_bp tracepoint Date: Sun, 4 Oct 2026 01:01:10 -0700 Message-ID: <20261004080110.37328-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20261003202727.3673-1-ravis.opensrc@gmail.com> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Ravi, On Sat, 3 Oct 2026 13:27:27 -0700 Ravi Jonnalagadda wrote: > Add a tracepoint for DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP quota goal > evaluation. The tracepoint fires once per quota-score computation when > the goal metric is DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP, exposing > context_idx, scheme_idx, nid, target_value, and current_value. > current_value is reported as the quota tuning sees it, after the goal's > complement setting is applied. > > The DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP metric expresses node memory > occupancy as basis points of eligible bytes. This information is not > exposed through any existing external interface (perf stat, /proc, or > sysfs), so the tracepoint is the only way for userspace to observe the > target and current eligible-memory basis point values at quota-scoring > time. Thank you for this patch! We have damos_esz tracepoint. Have you considered using it? It doesn't expose the current value, though. I thought it wouldn't be real problem in most cases, but I can show it could be problematic for node_eligible_mem_bp case, as the metric value is not straightforward to see without using DAMON. If you really need to know the current_value, I'm open to add a new tracepoint. But I think it has no reason to make it only eligible_mem_bp specific. How about adding more general purpose tracepoint, and/or update the current_value file [1] under the goal sysfs directory to show the current current_value for all goal types? [1] https://origin.kernel.org/doc/html/latest/admin-guide/mm/damon/usage.html#sysfs-schemes-quota-goals Thanks, SJ [...]