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 4200A3C660C; Tue, 5 May 2026 19:00:10 +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=1778007610; cv=none; b=Vqg5amDzcFjvN46J2ADpcWr044lWhv39kEO9HpNcqzIbjdru0404z/5JtM1BlnXeJuMFN6KwZAm7DzoapsSdhdrwAPav5GZTvTeNFNOCrUFvRB74pmBVfdIa+mGlIikyv0a9tP4MZ3xl9743uil6tMD7LyugJ93coVHLFv5zhJU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778007610; c=relaxed/simple; bh=hUj4YFzyO1VXcjqqW/XO6RlSLO5yLEQJ7wt0RMQ7kic=; h=From:Subject:Date:Message-Id:MIME-Version:Content-Type:To:Cc; b=aZCQ9nnOosFcwqrb2amcFf4jN/zK+uM091YDQtRxzggdQ6n8LCZtuG9Ut9dEg8phfqWJFWu+avyYOsYtgxuhg86Z7i3F612aehBPWw9yefhQihEdHHilgqsMKHSd4VHkso1mre1+kj3KTFgZrvbyGNZTpc8DIouGL2szeDvDS8I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HrzyDmIi; 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="HrzyDmIi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A648C2BCF4; Tue, 5 May 2026 19:00:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778007609; bh=hUj4YFzyO1VXcjqqW/XO6RlSLO5yLEQJ7wt0RMQ7kic=; h=From:Subject:Date:To:Cc:From; b=HrzyDmIi/+ayr0xH1WwgbouUwEqFC8bCu87Q2Vsyqpik6u3B2amiBcibYEJOAAHd4 TcI/Re8FV9tRgjkPEjygpHYLnh2nowtaKL+o+A2qW5ORWlAcGz6sdClgD4iCx3LwJC apNag9aoicNru0W117LCEgWF6wcE6IFDzAZkGodw8hWICUank7K88/J6YOHhm99O0F NKwFBiWe2g4Dlv5C1ddhdThbqmrPyS1OBtIXuQXv4FP90gvzYJndUrAiABf5yRPHey rgDlgHsrKH2WCSMq5jkdX1IT6Hcma7Y/KYDRZR2XPe+k2XTNaJ8/Lb8TX/aJzEGdnB 7cq6RDQxX3XbA== From: Jeff Layton Subject: [PATCH v6 0/2] mm: improve write performance with RWF_DONTCACHE Date: Tue, 05 May 2026 20:59:47 +0200 Message-Id: <20260505-dontcache-v6-0-66463805dd6a@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAAAAAAAC/23Oy07EMAwF0F8ZZU1QHnbSsuI/EIs8nGkEalE6q kCj/jue2ZBRWV7L59pXsVKrtIqX01U02upal5mDezqJNIX5TLJmzsIo4xQoLfMyX1JIE0kctKa SPYViBe9/NSr1+9719s55qutlaT/36k3fpv+1bFoqqQt6cCVE8OH1g9pMn89LO4tbzWZ6OvTUM B1hyJQ0eXTxQG1HjeupZepHitbnMCL4A4U/io8PA1PMSC4nr1O0B4o9hZ4iU9DKEg6RTz9e3ff 9F4+r6G6PAQAA X-Change-ID: 20260401-dontcache-5811efd7eaf3 To: Alexander Viro , Christian Brauner , Jan Kara , "Matthew Wilcox (Oracle)" , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Mike Snitzer , Jens Axboe , Ritesh Harjani , Chuck Lever Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-mm@kvack.org, Jeff Layton X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=3145; i=jlayton@kernel.org; h=from:subject:message-id; bh=hUj4YFzyO1VXcjqqW/XO6RlSLO5yLEQJ7wt0RMQ7kic=; b=owEBbQKS/ZANAwAKAQAOaEEZVoIVAcsmYgBp+j4ut1McCVLFPCo4dnsOZJGkCnEndrsyYF/ov 9xNqF5D4CGJAjMEAAEKAB0WIQRLwNeyRHGyoYTq9dMADmhBGVaCFQUCafo+LgAKCRAADmhBGVaC FSXyD/9Ab7U6obJOZVWw7dNHbbxmdELBm7YXZHN+bn0wBFwoMj8LnuLVgv9qzU6BB1iH8cwjSxw uIooxJ++hQh8paEqfZJxOb0wGg/SvhljFvg3ClKT5twqy0/uf+MBunz8MMiNgZGEYns+m/Ip2QG FIBVdQ9Jwavv7s7XffR0Z4I30uo0TIYNgA+iE+MC9YAQBF3Jldv+uWLtJNK/VI0a33x95PSH08r 3yzXhSP+9zm/2TKeow2JnqwoKMeXCSoRsAujGJ8HWjSVeavOkFp1tgWhF8hildAohpnYVOd8zG8 nEeHwA8noNTnO4s5VltTqf5P2FkPZBzOvW1Xe+1Ecxt/NSQdMGQ3T/wUdOeZeSQhHveJ6JktJV6 LrvHxfsS738cNfr+gM/6FbPd4l4TNgdJlOzsQkybiRhj/62/3i+x9DrEl1uy6d0wa1o3SrOFnKP nK4Jb/6tJzpueCWu7NwafB8lI/S8l9ZXeFzPi/Qg/baSVF4yavGKIXI0tFnAz/cb3zp+lCyZXni ifs0gDEz1lH0n4r/yrx2xbFy+zXKu3FaXT347PWK+F3zwOQq4PodXAVLXce7YyNR3zL7LdbI3TD in1EB020peBLAmtzhm+CyNWNOTpGjPfahPjO0pD8XRHBwbyakYeNigDU1b/T//hUzln2NxpQzTR fJIV5ho33fvdWdg== X-Developer-Key: i=jlayton@kernel.org; a=openpgp; fpr=4BC0D7B24471B2A184EAF5D3000E684119568215 This patch series is intended to improve write performance with RWF_DONTCACHE. After sending v5 yesterday, I decided to check what Sasiko thought about this series, and lo and behold it had found a number of bugs that I had missed before. This set should fix them. Performance is identical to the v5 set. Because there are some substantive changes in this set, I've dropped the R-b's. Please resend them if you're OK with this version. Christian, please consider these for v7.2. Thanks, Signed-off-by: Jeff Layton --- Changes in v6: - Use atomic folio_test_clear_dropbehind() in __filemap_get_folio_mpol() to prevent double-decrement of WB_DONTCACHE_DIRTY by concurrent readers - Add mapping_can_writeback() guard before decrementing WB_DONTCACHE_DIRTY in __filemap_get_folio_mpol() to match the increment path - Use wb_stat_sum() instead of wb_stat() in wb_check_start_dontcache() so small writes below the percpu batch threshold are visible to the flusher - Use test_and_clear_bit for WB_start_dontcache before starting writeback to prevent lost wakeups from concurrent DONTCACHE writers - Move wb_wakeup() outside the unlocked_inode_to_wb_begin/end section in filemap_dontcache_kick_writeback() to avoid spin_unlock_irq() re-enabling interrupts while the i_pages xa_lock is held during cgroup writeback switch - Drop Reviewed-by tags due to substantive changes - Link to v5: https://lore.kernel.org/r/20260504-dontcache-v5-0-4103e58bb377@kernel.org Changes in v5: - Flesh out comment over filemap_dontcache_kick_writeback() - Drop testcases from posting - Link to v4: https://lore.kernel.org/r/20260501-dontcache-v4-0-5d5e6dc71cb3@kernel.org Changes in v4: - Track DONTCACHE dirty pages per bdi_writeback - New benchmark for competing buffered and dontcache writers - New benchmark replicating Jens' original 32 concurrent writer test - Link to v3: https://lore.kernel.org/r/20260426-dontcache-v3-0-79eb37da9547@kernel.org Changes in v3: - Track dirty DONTCACHE pages in the VM - Have flusher write back a proportional number of pages after DONTCACHE write - Link to v2: https://lore.kernel.org/r/20260408-dontcache-v2-0-948dec1e756b@kernel.org Changes in v2: - kick flusher thread instead of initiating writeback inline - add mechanism to run 'perf lock' around the testcases - Link to v1: https://lore.kernel.org/r/20260401-dontcache-v1-0-1f5746fab47a@kernel.org --- Jeff Layton (2): mm: track DONTCACHE dirty pages per bdi_writeback mm: kick writeback flusher for IOCB_DONTCACHE with targeted dirty tracking fs/fs-writeback.c | 59 ++++++++++++++++++++++++++++++++++++++++ include/linux/backing-dev-defs.h | 3 ++ include/linux/fs.h | 6 ++-- include/trace/events/writeback.h | 3 +- mm/filemap.c | 15 ++++++++-- mm/page-writeback.c | 6 ++++ 6 files changed, 85 insertions(+), 7 deletions(-) --- base-commit: 7e2326f4275c11652e1fdaae11de06159fef1d90 change-id: 20260401-dontcache-5811efd7eaf3 Best regards, -- Jeff Layton