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 27AED35893 for ; Sat, 11 Jul 2026 00:48:16 +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=1783730898; cv=none; b=u2rCgXmEtRvcISQkF+WYIKsbhmglx1zTqvBhJhEkwGIKhhVdXn5OVChZdOwn1AUhwxbV1j+oNPSzmunNVsByvNHCZ8sLPwxdJflSGfeeTTlIy560s3LFEZi8yLvUqYs8p3/v1M4iUNN4fU9zh2pcSAthbNSHUHOE+qR1a6LrXyg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783730898; c=relaxed/simple; bh=ADaFxoOBrVPWXcfWHiwezikS12zts1vGr5p2laul9fA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=fHx4Qqk3Bc1Ywfq7Ua3VmhJhr7As2ZMEnjK/polfbib1jbIXgEYnkzM3GYOtnjOntTbvHsdBo+fQpdfLJw+PJnfAbQuc6mouxYoihSUQrpBnxa8nD310ITypKWkHSz3ZiVg0ibjjlmU1+wyJMPoEScuwvDlkNYJYl5BjTIpt1kQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ww70I7W5; 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="Ww70I7W5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9CF641F000E9; Sat, 11 Jul 2026 00:48:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783730896; bh=keJRvvoXb7a+C2rqbZvxVwkrZ44rhADL7hXJjIb5du4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Ww70I7W5irrFISquCoyNMYIG8Ks4j5OpjEnZsrD7Uw0TxMVLj2Zf12P4DviQ8Qbkz Oxb3+Qf5t44AWgDoyZU6anCZgsVlVlQ65JimVoDfDxZGXzT0gmgMwHgfnvLOAQ4Zn1 BLoCeXMDGTlzgXDjArTKWI70r7Th8b247hxPncYZQOCjr1NgGizig8cNEnxZyfkzTI 1wFchlN0crpbiNNTsyord4vTte4nNbebxL/9n+glbd/e/Db+VxPyaR41HwA2bTFzQq TiFuO4K4IedtEbEuxqgWzCGIsK9AkGX2P6qD8ASu/uyGfDY8uoonfrvLbCniJpYEQ5 xi0BWEQUdDj3A== From: SJ Park To: SeongJae Park Cc: damon@lists.linux.dev, Ravi Jonnalagadda , Akinobu Mita , Andrew Paniakin Subject: Re: Roadmap for extending DAMON beyond pte-accessed bit Date: Fri, 10 Jul 2026 17:48:08 -0700 Message-ID: <20260711004808.32620-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260624145614.89437-1-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 Wed, 24 Jun 2026 07:56:14 -0700 SeongJae Park wrote: > On Mon, 25 May 2026 15:52:08 -0700 SeongJae Park wrote: > > > Hello, > > > > > > TLDR: Let's extend DAMON for data attributes monitoring, andd then further > > extend that for multiple access check primitives including page faults, perf > > memory-access events and optimized AMD IBS-like h/w feature drivers. > [...] > > Roadmap > > ======= > > > > Assuming you agree to use the data attributes monitoring interface, I suggest > > us to do the work in below roadmap. > > > > Milestone 1: PTE Accessed bit as one of the data attributes > > ----------------------------------------------------------- > > > > I will work on stabilizing and further extending the data attributes interface > > and internal framework to be able to support PTE Accessed bit. This may take > > no small amount of efforts, but hopefully doable by the end of this year. > > Let me share more detailed plan for this milestone. Nothing is set on the > stone. Everything can be changed on the road. > > The overall goal is, making attributes monitoring be able to do everything we > are doing now with PTE Accessed-bit based monitoring. It is needed because we > want to do everythin we can do now with the PMU/page fault-based DAMON. Also > it is needed because we will need to deprecate nr_accesses in long term without > breaking users. For this, below changes will be made. > > 1. Support moving sum for probe_hits > > nr_accesses is providing a pseudo moving sum for convenient and fast monitoring > snapshot retrieval. Data attributes monitoring results (probe_hits) is not. > To make attributes monitoring be a foundation for the future PMU-like things > based data access monitoring, we will first make probe_hits be able to provide > the psuedo moving sum. Currently two patch series for this purpose are posted > on the mailing list: > > - nr_accesses_bp infra cleanup/optimization > https://lore.kernel.org/20260622142139.30269-1-sj@kernel.org > - exposing probe_hits pseudo moving sum > https://lore.kernel.org/20260621214231.13449-1-sj@kernel.org > > I aim these to be merged into the next merge window (7.3-rc1). > > 2. Support attrs-only monitoring > > As a next step, we will add an toption to stop doing the PTE Accessed bit but > only attributes monitoring. It will allow users to set weights for each probe, > and do the regions split/merge operations based on the weighted average of the > probe_hits. In this way, DAMON can run in two modes: access + attrs and > attrs-only modes. As of this writing, two patch series [1,2] for the above two changes are merged into mm-new. The mm-new having the second change is not yet pushed to the repo, but definitely queued [3] for. Hopefully those will be merged into 7.3-rc1. > > 3. Extend attrs for PTE Accessed bit check > > Further, we will extend DAMON attributes monitoring to handle PTE Accessed bit > check. We will extend it to let users configure probing preparation > operations. The first operation to support will be the PTE Accessed bit > clearing operation. Together, we will introduce new DAMON probe filter that > checks the PTE Accessed bit. Using those, users will be able to do the > PTE Accessed bit based access monitoring in attrs-only monitoring mode. I have a hacking level prototype for this in damon/next tree. I will take more time for stabilizing it. I'm aiming to make this be merged into 7.4-rc1. > > 4. Extend attrs for DAMOS > > Finally, we will extend DAMOS to be able to run with probe_hits. That is, it > will be extended to let users configure the DAMOS target access pattern and do > its quota-prioritization based on the probe_hits. > > After the four major changes are made, the attributes only mode DAMON can do > everything current DAAMON is doing, without nr_accesses. We will then move on > to the milestone 2 of this project, and start a long term nr_accesses > deprecation. > > I hope all changes to be landed by 7.5-rc1. So I believe we are still on the track :) [1] moving sum: https://lore.kernel.org/20260703170605.94472-1-sj@kernel.org [2] attrs-only: https://lore.kerrnel.org/20260710134651.18084-1-sj@kernel.org [3] attrs-only enqueue notice: https://lore.kernel.org/20260710202349.2F2DA1F000E9@smtp.kernel.org/ Thanks, SJ