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 21A4F13A258; Wed, 4 Feb 2026 00:29:07 +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=1770164948; cv=none; b=hLDqnI0ycN5u17Zg0F8n+ltKZBSRxulkKMgoe8YG1KMTU13VWbRA2n0L49OfXe9crZwxTnzjuATyJ+u1e60RpLK8Q0bK+36W6Iacptxt6zoUynB/ZxWIPtu79xMHICy6tMh2GmwTRjKWR14NabHT4N3h7TxeEAHoWHuQMRNg4xU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770164948; c=relaxed/simple; bh=qXE3g6jBKd0Y66pW7cPox46N88wlCWyAaIJYLCmu0uQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=RaKrN1TYsSp/Iu7SgPqHEZqzpGH5V7sWTkLInlTsmZr0v1XVsxk42XPq4vg3WopbkULekHFyBT4AK7YS4LJD14eG2Oji08mfgBrXpd3l+t3XDCGsSi3pwyMCgyScp7JCWu0vWYKKXo/beIHJ4Q4119DqKOUwOzOznXheeB3+CxU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IU8Q6VfB; 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="IU8Q6VfB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6442BC2BC86; Wed, 4 Feb 2026 00:29:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770164947; bh=qXE3g6jBKd0Y66pW7cPox46N88wlCWyAaIJYLCmu0uQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IU8Q6VfBQMpLFZ67aNKfIJIqzkP9TvOhTNtI59fwSZSXV6YqPxKwrWdmpHBv1dwSg 0VX5XZAN2rHTJ0fg32vC10Tsf1IkW0dCshjF1o730hypxasYnFn7LYpV9dECkI+2ji ID09hCOwY7aUJJA2j5qoXyaGuhMo+MWELNg3FAYKxAf5zf6fdPhQ/ZaqY5ZxiM/zKn G7+fEneH8mR2fRK4JYehWvbxOT9ag3t7+WbSuwXO99Hwcpf/mqviuc1hWzmw4/IHbz 7aGM2i79izcajfS5FS0mr/49sCoZxV1zCtmF82l5Sy08MXY7wRjrxOR27yq85g47gW mtTmJPdG6tunw== From: SeongJae Park To: Ravi Jonnalagadda Cc: SeongJae Park , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, akpm@linux-foundation.org, corbet@lwn.net, bijan311@gmail.com, ajayjoshi@micron.com, honggyu.kim@sk.com, yunjeong.mun@sk.com Subject: Re: [RFC PATCH v2 0/3] mm/damon: Introduce node_target_mem_bp Quota Goal Metric Date: Tue, 3 Feb 2026 16:28:58 -0800 Message-ID: <20260204002900.49291-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On Tue, 3 Feb 2026 11:48:06 -0800 Ravi Jonnalagadda wrote: > On Sat, Jan 31, 2026 at 11:54 AM SeongJae Park wrote: > > > > On Thu, 29 Jan 2026 17:48:06 -0800 SeongJae Park wrote: > > > > > On Thu, 29 Jan 2026 13:58:11 -0800 Ravi Jonnalagadda wrote: > > > > > > > This series introduces a new DAMON quota goal metric, `node_target_mem_bp`, > > > > designed for controlling memory migration in heterogeneous memory systems > > > > (e.g., DRAM and CXL memory tiering). > > > > > > > > v1: https://lore.kernel.org/linux-mm/20260123045733.6954-1-ravis.opensrc@gmail.com/T/#u > > [...] > > > Context 0: monitors node 0, migrate_hot -> node 1 > > > goal: node_ineligible_mem_bp, nid=0, target=4000 > > > > > > Context 1: monitors node 1, migrate_hot -> node 0 > > > goal: node_target_mem_bp, nid=0, target=6000 > > > > In offline, Ravi enlightened me that using a single context with two schemes > > instead of the above two contexts setup can be more efficienct and useful. I > > agree that. It will be able to only single kdamond, and there could be more > > flexible use cases that can use the whole-memory access pattern. > > > > That is, we can use single context with the two schemes, but adding a core > > layer DAMOS filters for applying the schemes to only memory of node 0 and node > > 1, respectively. Similar for memory tiering use cases. > > > > But I was recommending the multi contexts approach to people because the > > current implementation of DAMOS is not efficient when both quota and core layer > > filters are used. I was actually working on making it improved, and just > > posted an RFC patch series [1]. After the patches are merged, hopefully the > > single context approach will be useful and effcient enough for varying use > > cases including the memory tiering. > > > > [1] https://lore.kernel.org/20260131194145.66286-1-sj@kernel.org > > > Thanks for providing the DAMOS_FILTER patch update SJ. > > For v3, I plan to introduce two complementary metrics: > DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP > and DAMOS_QUOTA_NODE_INELIGIBLE_MEM_BP. > > This will support the following approaches for hot memory migration: > 1. Single context with two schemes using both metrics. > (along with DAMOS_FILTER_TYPE_ADDR) > 2. Two DAMON contexts each using > DAMOS_QUOTA_NODE_INELIGIBLE_MEM_BP. Sounds good! > > Will provide more details on the implementation and usage in the v3 series. Looking forward to it! Thanks, SJ [...]