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imf18.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=lst.de; spf=pass (imf18.hostedemail.com: domain of hch@lst.de designates 213.95.11.211 as permitted sender) smtp.mailfrom=hch@lst.de ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1748959491; a=rsa-sha256; cv=none; b=ZlIKw5heLJrHFUUli3osnMFQvgu7NKmiJMadMRXMVVW8ANFGFq3DyFO+Ss02ilkbE30ku4 c98oOKmlTNHfbK5DnK/790IQnBZCvy6DVcRugKqID/nO+RJIe/C6TXReyg1kdlQzVqG58q rvp+5T821ayH0IVRdIu93oJ5JHpAkGw= Received: by verein.lst.de (Postfix, from userid 2407) id 727C668D0F; Tue, 3 Jun 2025 16:04:45 +0200 (CEST) Date: Tue, 3 Jun 2025 16:04:45 +0200 From: Christoph Hellwig To: Anuj gupta Cc: Christoph Hellwig , Anuj Gupta/Anuj Gupta , 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, akpm@linux-foundation.org, willy@infradead.org, mcgrof@kernel.org, clm@meta.com, david@fromorbit.com, amir73il@gmail.com, axboe@kernel.dk, 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, kundanthebest@gmail.com Subject: Re: [PATCH 00/13] Parallelizing filesystem writeback Message-ID: <20250603140445.GA14351@lst.de> References: <20250529111504.89912-1-kundan.kumar@samsung.com> <20250602141904.GA21996@lst.de> <20250603132434.GA10865@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: E9CF01C000F X-Stat-Signature: zm9jbnu86tkhqycq7n7o79yzkwktjao3 X-Rspam-User: X-HE-Tag: 1748959490-967089 X-HE-Meta: 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 jA2xtqXR Z9LWOZs7c14XrOiqyB+Ur4jkHSFYNzU5Y4sftS6PocAULXZPRuUDxJl3YiK4bZiujo122NYcynmHia1lSNEAN9zh0lyNjxn7+nwBCX9n+U9aDSijMqY93mCw7V31mNKOeJRonxxuFaWs92qulpPu0eYijx2CntRj6+WcsQ/5a9YKd4BX6HHQrCXwshgKc5hMZNlnH 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 Tue, Jun 03, 2025 at 07:22:18PM +0530, Anuj gupta wrote: > > A mount option is about the worst possible interface for behavior > > that depends on file system implementation and possibly hardware > > chacteristics. This needs to be set by the file systems, possibly > > using generic helpers using hardware information. > > Right, that makes sense. Instead of using a mount option, we can > introduce generic helpers to initialize multiple writeback contexts > based on underlying hardware characteristics — e.g., number of CPUs or > NUMA topology. Filesystems like XFS and EXT4 can then call these helpers > during mount to opt into parallel writeback in a controlled way. Yes. A mount option might still be useful to override this default, but it should not be needed for the normal use case.