From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 26AF4330B01; Wed, 27 May 2026 15:59:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779897579; cv=none; b=PRhA96na2bJGnC9RtFO4d+I4+FUfR7uqGlLuHD7UBdPnGhFC5Gv14bH3R0rbWYLEpki2lM3jUnWnUIfJML85iwcvJhebZUnwrqSRl7GAfp+VJyC41Ggq3Ty2fnQYMk6GdcfwPaycW1QIp0bHZqy8ofzHsMMmffvnoGk5OWmJw4U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779897579; c=relaxed/simple; bh=93hGzeUNZXSmgPP5rRVCOqylEsp/Noq5x/ntYlDk91Y=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Xnxuog08Msp3H4b6vU5bK368v3oysKUYP66PK0wLnn4YFyM9NfdIrQdvClSghZO0+fdMCpWxIS82jDMSOs3KJB9Ky4doC7nW1BlaaLhTumXxfVzpr8lbxY9QeoHep40ZbTgSivpprJVK7oXxs12hG2MOZR8C/RX8kcXKXzmnzsI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=RYqc0BD/; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="RYqc0BD/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6866E1F000E9; Wed, 27 May 2026 15:59:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779897577; bh=ky5x6VV8bGsiRibL4Mbeireh2/3HHtZ2G1qotL6tKkE=; h=Date:From:To:Cc:Subject:References:In-Reply-To; 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> Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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