From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 9DC133A63EB; Tue, 21 Apr 2026 22:36:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776811004; cv=none; b=hIgLYYx928DAoToeLVYLcgqNZPOJ0SXNJ6AJXz2aoydMFQOVvxGFnkJB0utS9+ircbnV/p4qk9m8+d3dryTZHJ2AcJ2S41EqAjhAitSFKO3xudFWNnoaU2+Z1Cm/PKvli4dFHkf7SrMLboVwMNF94gv+8VxR918kgEtR2N+TeoY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776811004; c=relaxed/simple; bh=rYR0EGH23chj/ciflhN3Y7j6+4nUJvtKtjJgmfOTNCM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=eD47B7FicTFXIEsSxQee9iCNkhPHfDBws17oFekYw/B8s6xqivpOoAIPP09S2N3VRkSYfzNRWTwZ7TPXKvJOrtyPi3ZdOCEMnzhrNKvFU5zE/Wz7ykPekSezZ5+Pam2rfKHDbpPYFBMf1NRkw/FHYHU3N/1wYwB8EyVvYM0c6wE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NZeqVzWu; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="NZeqVzWu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 20101C2BCB0; Tue, 21 Apr 2026 22:36:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776811004; bh=rYR0EGH23chj/ciflhN3Y7j6+4nUJvtKtjJgmfOTNCM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=NZeqVzWuq4Rdqk0BR09Dntk1fNswuCIsSupoE3qSDO7moEPj23S2jCqAC9WkNjAJr /hbqtMhhqkjbJkwDnPDyvQyowhWR0TIeq8HbK5gve2asVK9iNKtjefbho/OHys3DUV ZDKsQtubKlSSMPKeF+qzXF49C9zCY//xARTn6zqpq7qJPIwo0Cj8JPgBpMX4LP0D4J dU9Dw1breSgV4xDOmoqkdBh/pkSDM1MHlnkvlAP/cmKHoDm6f8D7QUOyD05p+9h2fC Akp6sj66DpNOm/6dk4D95m0a9uUxLmgNO+B33dRS08X3EqlDdylHxJ9tJMYY6gS9I1 Ro0mv57Kd9myg== Date: Wed, 22 Apr 2026 08:36:37 +1000 From: Dave Chinner To: Fengnan Cc: Ojaswin Mujoo , Fengnan Chang , brauner@kernel.org, djwong@kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, lidiangang@bytedance.com Subject: Re: [RFC PATCH] iomap: add fast read path for small direct I/O Message-ID: References: <20260414122647.15686-1-changfengnan@bytedance.com> <87674d63-c8cb-4135-8d76-84f52e90ac2e@bytedance.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <87674d63-c8cb-4135-8d76-84f52e90ac2e@bytedance.com> On Tue, Apr 21, 2026 at 11:19:31AM +0800, Fengnan wrote: > 在 2026/4/21 07:59, Dave Chinner 写道: > > I'm clearly missing something here. I'm trying to work out why the > > profiles show what they do, but there's differences between them > > that do make obvious sense to me. > > > > It would also be useful to have XFS profiles, because it has a > > larger CPU cache footprint than ext4. If what the profiles are > > showing is a result of CPU cache residency artifacts, then we'll see > > different profile (and, potentially, performance) artifacts with > > XFS... > The XFS flame graph is also attached now. > IOPS: 1.92M->2.3M. The callchains in both XFS flame graphs are completely bogus: .... io_read __io_read xfs_inode_free_eofblocks xfs_prep_free_cowblocks iomap_dio_rw iomap_dio_simple_read xfs_mountfs .... Can you regenerate the profiles, please, and this time check that they make sense before posting them? -Dave. -- Dave Chinner dgc@kernel.org