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Wed, 25 Jun 2025 08:45:01 -0700 (PDT) MIME-Version: 1.0 References: <20250529111504.89912-1-kundan.kumar@samsung.com> <20250529203708.9afe27783b218ad2d2babb0c@linux-foundation.org> In-Reply-To: <20250529203708.9afe27783b218ad2d2babb0c@linux-foundation.org> From: Kundan Kumar Date: Wed, 25 Jun 2025 21:14:51 +0530 X-Gm-Features: Ac12FXz-WfD7KDK7gS4t-j71iOt-puRRwIJfu8WaOkNNWXA_hJ1q0mugrvCoDS0 Message-ID: Subject: Re: [PATCH 00/13] Parallelizing filesystem writeback To: Andrew Morton Cc: Kundan Kumar , jaegeuk@kernel.org, chao@kernel.org, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, miklos@szeredi.hu, agruenba@redhat.com, trondmy@kernel.org, anna@kernel.org, willy@infradead.org, mcgrof@kernel.org, clm@meta.com, david@fromorbit.com, amir73il@gmail.com, axboe@kernel.dk, hch@lst.de, ritesh.list@gmail.com, djwong@kernel.org, dave@stgolabs.net, p.raghav@samsung.com, da.gomez@samsung.com, linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, gfs2@lists.linux.dev, linux-nfs@vger.kernel.org, linux-mm@kvack.org, gost.dev@samsung.com Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam11 X-Rspam-User: X-Rspamd-Queue-Id: C26D0C000E X-Stat-Signature: ewqk1jsrwj3zr3o1kbt3edcpxi83mfn7 X-HE-Tag: 1750866303-507809 X-HE-Meta: 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 2D9d0fxZ eO8hBkpaGMAPeILeL+UD74fS9WCamgoFab9IoZSPJrXsd3q+IfhjXgxRtXQN1t/2fKtdBTBT+MIkFSnTu1A6ywT8s7GCMBpDdSarOm6jL2/04E46vhLhFCLpbUCTI9f8xAGZjKnvMguvbHWE0YBmFiupDm3s1TpZsNpMX2PJNMsR4tCOeWvXwnUtCFJMDZ0iELFhyEhK4oj6BpZYQ97Cumwd6+QKtAaSpYFH00FyxeuyW9eDO6ZpBUGbpXSsgOVX+x1bHRDzwCpT1h8Lv+P2HJcb22rzv1DNzzNlP2OtuNbtWzy7AlVnj7EuPHO6wDnS36Gr3a7q0hHf0FJ3WW13ObTgBs1IZsD9nLOaWEv9/GpgNNYG9XzLbAwelmnCiERGOnjyGtTniK4/n43o= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > > Makes sense. It would be good to test this on a non-SMP machine, if > you can find one ;) > Tested with kernel cmdline with maxcpus=1. The parallel writeback falls back to 1 thread behavior, showing nochange in BW. - On PMEM: Base XFS : 70.7 MiB/s Parallel Writeback XFS : 70.5 MiB/s Base EXT4 : 137 MiB/s Parallel Writeback EXT4 : 138 MiB/s - On NVMe: Base XFS : 45.2 MiB/s Parallel Writeback XFS : 44.5 MiB/s Base EXT4 : 81.2 MiB/s Parallel Writeback EXT4 : 80.1 MiB/s > > Please test the performance on spinning disks, and with more filesystems? > On a spinning disk, random IO bandwidth remains unchanged, while sequential IO performance declines. However, setting nr_wb_ctx = 1 via configurable writeback(planned in next version) eliminates the decline. echo 1 > /sys/class/bdi/8:16/nwritebacks We can fetch the device queue's rotational property and allocate BDI with nr_wb_ctx = 1 for rotational disks. Hope this is a viable solution for spinning disks? - Random IO Base XFS : 22.6 MiB/s Parallel Writeback XFS : 22.9 MiB/s Base EXT4 : 22.5 MiB/s Parallel Writeback EXT4 : 20.9 MiB/s - Sequential IO Base XFS : 156 MiB/s Parallel Writeback XFS : 133 MiB/s (-14.7%) Base EXT4 : 147 MiB/s Parallel Writeback EXT4 : 124 MiB/s (-15.6%) -Kundan