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b=RYqc0BD/c9Rk6VG80/Ku4juq+/5NhEA9655oRwH1Wmuep9DRWmqdGxTBZaGOAbx4c tAWp51YEvq1+8lth6riLToTePL3f5jhd0A9B+eajyaSW8fHPYWYjSs9849zYuwPqKi SkmrQ1Sj73F1X2nwofk44uZKbCtcjtNxLKSdqk50qPKRabEVz9ZGdCeRb9P/jUX7Gp ROw64V0uXEJeCATrY80FENgdTyVVifxFzRe5FtVsGqwU6po13npcbonInSgIoCh8L0 uwTj53KmkgZ1MFEdp8hsLXFebtZo4DHZROQbE1pFiS8JcRGFroxsy56nkfPhdv80xj RmK8vLj9DyWvQ== Date: Wed, 27 May 2026 15:59:35 +0000 From: Jaegeuk Kim To: Christoph Hellwig Cc: Bart Van Assche , Theodore Tso , linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, Matthew Wilcox , linux-f2fs-devel@lists.sourceforge.net, linux-mm@kvack.org, Akilesh Kailash , linux-fsdevel@vger.kernel.org, Christian Brauner Subject: Re: [f2fs-dev] [PATCH v2] f2fs: another way to set large folio by remembering inode number Message-ID: References: <20260521155748.GA79343@macsyma-wired.lan> <20260522141115.GA8258@macsyma-wired.lan> <20260522224108.GA18663@macsyma-wired.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: C89E7180006 X-Stat-Signature: 8khkypu7psjhjwkutkt6qgoj4qio4mwd X-Rspam-User: X-HE-Tag: 1779897578-28229 X-HE-Meta: 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 B3doZSPQ Cobn7h69GKIdlp6VRsRVr/FAJbFpSXWVJb1bHvUCwFu/NTLHutC7ZBQFyTrkGIRACOVLAreR1Pdi1afhVzzCKYFDMUsp7Rt2qUw2+uW1AwbPBHlQarhH6GYeqci5F18rFOk1ga/mq1xvkry5+pSazsMi/E25AmzDvMDNGwwLAhVsNYM7KbiWx5e1RFVtaBxaAmXBaRZ1oI1tHE+Uf83cnNI4Jlbphk77WkzrPRelmwpNXpsl8Nz/mGRc0qY6ORIo9S0VfLSvX8738oz+2i9dKUq8eBQzkbm9Xh2KGfB1lEK7tYxlEn58MLtRfKg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 05/26, Christoph Hellwig wrote: > On Tue, May 26, 2026 at 09:14:52AM -0700, Bart Van Assche wrote: > > On 5/26/26 6:42 AM, Theodore Tso wrote: > > > It seems... surprising that the additional I/O operations are actually > > > throttloing UFS device bandwidth by 2x (4GB/s vs 2GB/s). Have you dug > > > into why this is happening, and whether there is anything that can be > > > optimized below the file system? > > The layers below the filesystem (block, SCSI, UFS) is what I'm > > responsible for in the Pixel team and I can assure you that these are > > highly optimized. > > > > Since the transfer size used in Jaegeuk's tests is much larger than 4 > > KiB, how many CPU cycles are used per IO by the layers below the > > filesystem is not limiting the transfer bandwidth. > > I'm honestly not sure what discussion we have here. Larger I/O is > pretty much always more efficient. If you submit smaller I/O you > need more merging to build it back up larger, and more I/Os. F2FS merges bios before submit_bio, regardless of small or large folios, since the block addresses are consecutive. So, I think IO subsystem was working in full speed. > > Which is exaxtly why we need large folio support everywhere, as it > makes a huge difference in I/O performance. > > > > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel