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 8B4BC3624A5; Sun, 13 Sep 2026 17:11:42 +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=1789319503; cv=none; b=nByfaY4DqQ7BLjYXiUyIltb/ZUhE0EGsYF93mD8pEU33VzqqaDRUdRWc3nTDH6wakDnAZtFDv3BYuQCef1WYqk/rocltueoRB/Dc/7OAUG2zKA227SnUgTFagUy7Q6w92bSaEGWBtbISQDUnhh+youn+zh1IAHNwbysG2V/Amw0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789319503; c=relaxed/simple; bh=+sIdpXfxlsc4yuIGGMUlFltyY0YTPsT2xoJif27dxFM=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=FfJhFe0mAYW8oe6JwugdZpHp/aJf3hckKuRg2KTb78OPO3XdAyj4KwGmH8okejeHpkRVUbZjt5MHzjvUoiluQUio5bLXqTzJQOHVtW/dyzlAcH1ZqIRHw6sA1nRtdQyfZvN/NaUUGSg1s+OsuQ6oky70YT8WtizOznQTXjdHB9c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jqZAw3Sv; 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="jqZAw3Sv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 943271F000FF; Sun, 13 Sep 2026 17:11:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789319502; bh=2ZHtfSZyRuUi4qVh2TQmjcCNtITXl+b4Bizxwjd/UP8=; h=From:To:Cc:Subject:Date; b=jqZAw3Svg9VeStTqsuM2WGZ+gm8UQ5KiloAG7a6ktDPvG+XICMq1upxg7wh3hAfBJ CXwKLNfw3naYioZJon5rKR+hh5FyF84I/D0hUpfWnB77tR496PigKftzDqpq79B5E6 jv2VSCIWSQ1b5DHYE6bepvZKyt39g4Z+MCHDl6WMdQNb1HcW6OLciWpOih4E7xHpmn QmUqDPfh6KvDAywF4LsNCGY6GQhO1b1YKWJPVTiCUmOcor7zRvmpSoh/UMTiqXJuyw MYSnz1ogFepuEuwiZAWChIMSzzFKdNehxDA8wdDLTPQNHmGxRST1RKk2WIduca091T NytkNKwAGv8AQ== From: SJ Park To: Cc: SJ Park , "Liam R. Howlett" , Andrew Morton , David Hildenbrand , Jonathan Corbet , Lorenzo Stoakes , Michal Hocko , Mike Rapoport , Randy Dunlap , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , damon@lists.linux.dev, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH 0/8] mm/damon: introduce hugepage_size probe filter Date: Sun, 13 Sep 2026 10:11:22 -0700 Message-ID: <20260913171133.102366-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Knowing whether a given memory is backed by a hugepage of specific size is useful for efficient utilization of hugepages. For easy monitoring of the information, introduce a new data attribute probe filter type, hugepage_size. It works similar to the DAMOS filter of the same name. It works for memory that is backed by a hugepage of a given size range. Patch 1 introduces the new probe filter type to DAMON API and extends related data structures. Patch 2 updates probe filter commit logic to handle the size range. Patch 3 Updates the filtering logic to support the new type. Patch 4 adds new DAMON sysfs files for the size range. Patch 5 updates DAMON sysfs interface to fully support the new filter type. Patches 6-8 updates design, usage and ABI documents for the new feature. Test ==== Set THP always and start a test workload using masim [1]. $ echo always | sudo tee /sys/kernel/mm/transparent_hugepage/enabled $ ./masim.py run --config_file ./configs/stairs-500mb.cfg --repeat 10 Using the DAMON user-space tool, damo [2], start DAMON with two probes. The primary probe monitors access. The secondary probe monitors 2 MiB sized hugepages. The region adjustment weight is given to only the primary probe. That is, this setup is for showing access temperature and additionally how many 2 MiB hugepages are being used for the region of the access temperature. $ sudo ./damo start $(pidof masim) \ --probe_prep set_pgidle --probe_filter allow pgidle_unset \ --probe_filter allow hugepage_size 2M 2M --probe_weight 1 0 \ --nr_probe_preps 1 0 --nr_probe_filters 1 1 --nr_probes 2 Show the monitoring results. $ sudo ./damo report attrs heatmap: 000004[...]666666668988888888888844444430000000000000000000000000000000000000000000014[...]8 # min/max temperatures: -470,000,000, 10,000,500, column size: 64.119 MiB probes - prep: set_pgidle, filter: allow pgidle_unset (weight: 1) - allow hugepage_size [2.000 MiB, 2.000 MiB] (weight: 0) intervals: sample 5 ms aggr 100 ms (max probe hits 20) # size address age probe_hits 0 354.039 MiB 85.833 TiB 4.700 s 0 0 1 1.843 GiB 127.724 TiB 4.700 s 0 6 2 936.781 MiB 127.726 TiB 4.600 s 0 16 [...] 25 44.000 KiB 127.723 TiB 0 ns 15 20 26 11.492 MiB 127.723 TiB 0 ns 16 20 27 2.160 MiB 127.723 TiB 0 ns 19 20 [...] 47 376.000 KiB 127.723 TiB 300 ms 1 20 48 48.000 KiB 127.723 TiB 400 ms 2 20 49 812.000 KiB 127.723 TiB 500 ms 9 20 memory bw estimate: 0 B per second total size: 5.009 GiB record DAMON intervals: sample 5 ms, aggr 100 ms The first probe_hits count and the age show the access temperature of each region. The second probe_hits count shows the ratio of 2 MiB hugepages in the region. For example, region 2, which has 936 MiB size, is quite cold (not accessed for 4.6 seconds) but uses 2 MiB THP for ~80% (16/20) of the region. Maybe not a very efficient use of THP. On the other hand, region 49, which is 812 KiB size, is somewhat hot (accessed about 9 times per 100 ms for the last 500 ms) and fully backed by 2 MiB hugepage. Maybe this is a good use of THP. [1] https://github.com/sjp38/masim [2] https://github.com/damonitor/damo SJ Park (8): mm/damon/api: introduce DAMON_FILTER_TYPE_HUGEPAGE_SIZE mm/damon/core: commit hugepage_size type damon filter mm/damon/ops-common: support hugepage_size damon filter matching mm/damon/sysfs: add min,max files under probe filter directory mm/damon/sysfs: support hugepage_size probe filter Docs/mm/damon/design: update for hugepage_size probe filter Docs/admin-guide/mm/damon/usage: update for hugepage_size Docs/ABI/damon: update for hugepage_size probe filter .../ABI/testing/sysfs-kernel-mm-damon | 14 +++++ Documentation/admin-guide/mm/damon/usage.rst | 4 +- Documentation/mm/damon/design.rst | 2 + include/linux/damon.h | 8 +++ mm/damon/core.c | 20 +++++-- mm/damon/ops-common.c | 10 ++++ mm/damon/sysfs.c | 55 +++++++++++++++++++ 7 files changed, 107 insertions(+), 6 deletions(-) base-commit: 91c120b49e83b867e29684fd229c3e1f07190071 -- 2.47.3