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Wed, 29 Oct 2025 06:05:24 +0000 (GMT) Message-ID: Date: Wed, 29 Oct 2025 11:35:21 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 00/16] Parallelizing filesystem writeback Content-Language: en-US To: Christoph Hellwig , Dave Chinner Cc: 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, akpm@linux-foundation.org, willy@infradead.org, mcgrof@kernel.org, clm@meta.com, amir73il@gmail.com, axboe@kernel.dk, ritesh.list@gmail.com, djwong@kernel.org, dave@stgolabs.net, wangyufei@vivo.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, anuj20.g@samsung.com, vishak.g@samsung.com, joshi.k@samsung.com From: Kundan Kumar In-Reply-To: <20251022043930.GC2371@lst.de> Content-Transfer-Encoding: 7bit X-CMS-MailID: 20251029060545epcas5p491529ef7b75758f4d8bc82f4da1b9976 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" CMS-TYPE: 105P cpgsPolicy: CPGSC10-542,Y X-CFilter-Loop: Reflected X-CMS-RootMailID: 20251014120958epcas5p267c3c9f9dbe6ffc53c25755327de89f9 References: <20251014120845.2361-1-kundan.kumar@samsung.com> <20251022043930.GC2371@lst.de> X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 7173510000C X-Stat-Signature: 754w5gn59surpujbyd1rbzn89q19xjri X-HE-Tag: 1761717951-780174 X-HE-Meta: U2FsdGVkX185ZcnGAVfRW0T+ktsmoNS38syIR021kkekOV8PKUKdtmOEPp7+F+LrwZqlCrSkCHWEgisH7qJ0794Cn4Sizj8/eb7MsyHeFeEELTnozIdH1FwP3QUbA8lZE12SDhaeHzeU+wsaVzIahb0JVWR5nbrN/eOZG2b+0+Tb0IDgmmhEWkwSJ9Jv8/VEspZyapWpzkO3hMr0/NM1Aie7KUUw0Odw3SK0nh7kLnUl8R0ZkY1ynop3FKdQUn05wrXAZj0KDreCgCUGwH04mIIeLEhuQ5L4zNVdSvbzW0p3Mw748qVlxhHoI5Fj8VVPpZABs/NCOWk7tvaKFIASXxlKyYRjJ+3nlFelT60ArtKcR3z96ovxKerUKNtqfu2Hp50NR9IQDwQxuSfhE691NrqCe4C/dugjpR6QlyBESAnRJ9lW4igq57CvD/xGixXrOQsS3D8DzlDjFfu0kFeqQ20pDtca9EDN6iAkAAg0i08miSGmHo3JVqA/LG1fdKduCAM4yQFNgo+LTUTqI93FDBeXm6N3ueGxZtDaVwscPJih3AJ1ZZ/nZ2vBzw5kt5DBeq4GnbSK07qb3smwDlHHy3gpjRrO8zxSlfgqJpGP4RNS+o+7meBxp6o9X32tZvI4pH+8FOnq+LHtv6q95hdOgs4pSLQx/y77CpWftwffqvGj/eWGUZsw2wlBIOHIpQo7cj5djzhQxD3ZG7zON1IpY8hgyn78fesFNAMT4dDTUnukTPZGhGRn54JHVNRLeWh0vD9Pcy5r7BjcPiP740Kt4nEDTxIcIZ1rwEQ1CpIYi80mtKiQSOiZt+Jo2eWyvHvQG6MWZ5wvGzEYRfD9l181tOpSbDxCR0lg1prTC6AVV+ziP4in7URLq4NfqEverQrxLDq2jsX9uivNLjK1bVPqCMxE3JzJuN5QI0a+5H/3cLZXloykWvePlJHYLLVlS+th1/h6ie52SqqdkhWLukZ ZTwV8v6f 0hsL8tD1GaTnvcXFRsV1Q8MVKqxnj+MF33W9kVXj0KYILbOyrcjWCfsXrAHCSbb4ROZSyfHULCuv1Cj12qg9EbsdcTf3uMF04fvsmJESPCdw7/2jMDZBExIzseXkujlWivo4bBZV/ALsIMVG2xl0Sa+3PNoVOeADvz85DfPEquFJJFzNfhWI4xLKqrOLM4Wbw79pmZYvfGh3JUWo= 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: On 10/22/2025 10:09 AM, Christoph Hellwig wrote: > On Tue, Oct 21, 2025 at 09:46:30AM +1100, Dave Chinner wrote: >> Not necessarily. The allocator can (and will) select different AGs >> for an inode as the file grows and the AGs run low on space. Once >> they select a different AG for an inode, they don't tend to return >> to the original AG because allocation targets are based on >> contiguous allocation w.r.t. existing adjacent extents, not the AG >> the inode is located in. > > Also, as pointed out in the last discussion of this for the RT > subvolume there is zero relation between the AG the inode is in > and the data placement. > > I evaluated the effect of parallel writeback on realtime inodes and observed no improvement in IOPS. We can limit writes for realtime inodes to utilize a single default (0) writeback context. Do you see it differently?