From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 880973D0C2; Sat, 27 Apr 2024 04:47:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714193226; cv=none; b=MJyEf6RehSeQ6o6eOm5xqn6kUpdtcrAVNS7h6pxZDz6xZfd6ROqzXLnhCLOlm2H3dexZT9mygXx9tR7SLc/l38n5K2zUrN1SSVL6A0SCI5mSjJgitO692sr++jWGq4w7s27WcxPPQOt47hZnuY0CUlT8gEt16l85SZc6fgBnTNM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714193226; c=relaxed/simple; bh=LRCIkuejIh2ioIHP5AzHL7iNdWGaOmpp8+XXWy0KtuY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=oInT/+/IL6sqA+bJT7Fcq173XDT302+FVMobaDp75vdLv1J8zZiPcLa1EjOb/ubUaed7Z2GEUhSXNNgzhjOfyQfxNR6O2euwh19kExUZJLNIQJkFzW/dheCFPdfMlFK3vxqXF0FZkOWZyWa3ZccuTzeBcRm/xATWXJ5GV6bXZok= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=OBY8m/D7; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="OBY8m/D7" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=6xpU9VR8a6K2/jLYXQfcQD1fDuHqlmP2r7odFKj3g8U=; b=OBY8m/D7mwHz4ZirDPL3GuMhrA 1nIRnLfqU1zETqu5iRU3Xu42z5jxSSK1IGacS68+brIzlm3Q4G/lkhEyqC4y6zcOXJoKUDLf+CwWe LWZV/4oJydHICNuF4Lggf02Wy+tRXvF8/lwYWM44ZCNSpI3XkhJQ4WD/cinz4zdBGqGNR+9JxVwvG 81RoL+92Bvo4nmcNzMOlQeKnCDjAaeESx6cBSekseILTgr9zON0w1d6Hjcf8WK2kCihgtHLOLvWac RvfODVaiBpLNzqjK29Y061Mabsq4tVTI1QN4IdSJuUW62Ct3bhpgH4U60zksZext7EUEI5Sghc0lR mhlZBx3Q==; Received: from hch by bombadil.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1s0Zxn-0000000EonU-2S8c; Sat, 27 Apr 2024 04:47:03 +0000 Date: Fri, 26 Apr 2024 21:47:03 -0700 From: Christoph Hellwig To: "Ritesh Harjani (IBM)" Cc: linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Matthew Wilcox , "Darrick J . Wong" , Ojaswin Mujoo , Jan Kara Subject: Re: [RFCv3 7/7] iomap: Optimize data access patterns for filesystems with indirect mappings Message-ID: References: <4e2752e99f55469c4eb5f2fe83e816d529110192.1714046808.git.ritesh.list@gmail.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=us-ascii Content-Disposition: inline In-Reply-To: <4e2752e99f55469c4eb5f2fe83e816d529110192.1714046808.git.ritesh.list@gmail.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Thu, Apr 25, 2024 at 06:58:51PM +0530, Ritesh Harjani (IBM) wrote: > Currently the bios for reads within iomap are only submitted at > 2 places - > 1. If we cannot merge the new req. with previous bio, only then we > submit the previous bio. > 2. Submit the bio at the end of the entire read processing. > > This means for filesystems with indirect block mapping, we call into > ->iomap_begin() again w/o submitting the previous bios. That causes > unoptimized data access patterns for blocks which are of BH_Boundary type. The same is true for extent mappings. And it's not ideal there either, although it only inreases the bio submission latency.