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 72BFA3AE1B4 for ; Tue, 29 Sep 2026 07:49:37 +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=1790668178; cv=none; b=J7lde1nZnKEfpn4pbJjRaRR1cOUKavgRPFLNOP2WdsorkLSljdbipTznWi/OHG6WUQiuZm353rbD4nO1b/b74elBmvDSuCiqn4jrkpDGT5TskVj2PxsrZZi7loq2DnF0SbPhiNcnj3zNFYOwik7mff8hRIT9GWe6mKwueB3U0Vk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790668178; c=relaxed/simple; bh=7vwGVA1CH5yyx9BHzVr7wZ/CTvFXV0JWKiQicg87sfs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=txzC5ZsQxPv4mBjRLj1UsRx/EqeqzK1BZDuV/dPwma9aTxOEU83KP2TYyUSetCFSZRk+LT2DTfjBVtq9RBAc8i5pJG9JdQGIrTgwHP7el31hi6Oa+aLsGKeirNZxLlpDOl68YeeSiCrZU79orpBYwGMgooVCfsGkz3bqT/eZ4rY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZQ2YLwTa; 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="ZQ2YLwTa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1F9BC1F000FF; Tue, 29 Sep 2026 07:49:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790668177; bh=VPht9WNWFS86BiIEP+h7UzzhDcQB+WCi6crydl5nEfc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ZQ2YLwTaDIxcBYOoI4mOPIWSdq18GRFv0q0uZuqdTDWbALLjOcgVWdg3c+RKhLFR8 KGLhxQvQuq8Nzu3u+DFIbrXHCSvk1EaAqClpilK/dmOLZwyu6v4DXjlgXBgaubL2nJ vAldv3pr3TMd7LdzLwUC1LrcyLMrktiAbAnKsmHOjU7KVqXVnRPJQ0pA4luMYobMwF Wrw1QVcN3ce8xT3qSXPRoWsvYbwX5aTdiuEn8B89wfCXPMZte0CTvGeIklunC5oP8c wBERpyKX3RfOUBG3KNIpvxaB/tf8hZEsIulChpc24166BQ0C2V2/tXogOZDHkd5y6f gIPiqUKxX1Uxw== From: SJ Park To: Anton Gavriliuk Cc: SJ Park , damon@lists.linux.dev Subject: Re: Memory tiering with DAMON/DAMOS auto-tuning Date: Tue, 29 Sep 2026 00:49:32 -0700 Message-ID: <20260929074932.40176-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: 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 Mon, 28 Sep 2026 20:02:43 +0300 Anton Gavriliuk wrote: > > Thank you for sharing your use case and question! > > Thank you for your quick response and your answer/comments. > > We already had memory tiering implemented at hardware level 5-7 years > ago with Intel's Optane PEM when configured in Memory Mode. > Now we do the same thing at Linux level :-) Interesting! > I'm new at DAMON/DAMOS, there are lots of new tunables to me. Indeed there are. I'd recommend starting with existing DAMON-based memory tiering solutions including SK Hynix HMSDK and my auto-tune based memory tiering script [1] and ask questions to the authors. > > > The example memory tiering script [1] uses 4% as intervals goal. Is there a > > reason to use 97% as the goal instead? > > Oohhh... I moved to 5%. I understand you mean 4%? > > > Is the above node_mum_used_bp what you really want? That means you want to > > promote hot pages from node 2 to node 0, until the node 0 memory utilization > > becomes 99.7%. That overlaps with the demotion goal (50% free memory of node > > 0) quite a lot. I'd suggest smaller overlap, say, 50.3%, to keep healthy > > circulation of hot/cold pages while not consuming too much resource under > > stabilized access pattern. > > > DAMOS quota auto-tuning supports two tuner algorithms [2], consistent and > > temporal. As the documentation [2] explains, 'consistent' tuner assumes it > > should keep applying the action in a level to keep the goal achieved. In this > > case, for example, the demotion scheme assumes there will be continued > > promotion and therefore it keeps demoting. If there is no appropriate > > promotion, it could result in demoting more than expected amount. > > So let me firstly understand what I really want to test :-) Sure, and please feel free to ask any question in any ways. If you prefer to, you could also ask questions privately to me or use DAMON Beer/Coffee/Tea Chat series [2]. [1] https://github.com/damonitor/damo/blob/next/scripts/mem_tier.sh [2] https://docs.google.com/document/d/1v43Kcj3ly4CYqmAkMaZzLiM2GEnWfgdGbZAH3mi2vpM/edit?usp=sharing Thanks, SJ [...]