From mboxrd@z Thu Jan 1 00:00:00 1970 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 D3E1B54758; Fri, 12 Sep 2025 02:06:23 +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=1757642783; cv=none; b=N4XxahAdtpMLHn3gxQf9P6ZItIZnsxwuldad/XVAAamAm8GAzlhtYNCUWx3WfvtAkzK2C9prpYi948VGPj+76Jbxoclx/TDUC0N7A9yfI+NG4GZukx3XYM86iqRHNANMvtW/tJRz6sPWbRcyRnf8gBOjCUouBb4gO0fuVEFkOJY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757642783; c=relaxed/simple; bh=wEWmhx5I48s/7JlI41mY1TFXvMlPvtQErgtyGu0ct2E=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=mZOxl9oqm1mc2ffi4MSJuypP8iHVz6kEvzbVbVy9QYEyGsKibnwLkBN8mdYqQjcz5T+OaoM1WZLPGNLfGJLmjB0wTkesCo7Kb2Cq3k98pr/FYHvCpPQOyzoc3cXR0KyoSCmPaMD7DsiF/iSVLVFAaJ986lcp2fKji24jEVCs6Vg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YCPcERYv; 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="YCPcERYv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 59FBAC4CEF0; Fri, 12 Sep 2025 02:06:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1757642783; bh=wEWmhx5I48s/7JlI41mY1TFXvMlPvtQErgtyGu0ct2E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; 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: Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 [...]