From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 05C41C4167B for ; Fri, 10 Nov 2023 17:46:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232516AbjKJRqb (ORCPT ); Fri, 10 Nov 2023 12:46:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34238 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234766AbjKJRpe (ORCPT ); Fri, 10 Nov 2023 12:45:34 -0500 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1618F6F81; Thu, 9 Nov 2023 22:23:31 -0800 (PST) Received: by verein.lst.de (Postfix, from userid 2407) id F1E8068AA6; Fri, 10 Nov 2023 07:23:25 +0100 (CET) Date: Fri, 10 Nov 2023 07:23:25 +0100 From: Christoph Hellwig To: John Garry Cc: Christoph Hellwig , axboe@kernel.dk, kbusch@kernel.org, sagi@grimberg.me, jejb@linux.ibm.com, martin.petersen@oracle.com, djwong@kernel.org, viro@zeniv.linux.org.uk, brauner@kernel.org, chandan.babu@oracle.com, dchinner@redhat.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, tytso@mit.edu, jbongio@google.com, linux-api@vger.kernel.org, Himanshu Madhani Subject: Re: [PATCH 01/21] block: Add atomic write operations to request_queue limits Message-ID: <20231110062325.GB26516@lst.de> References: <20230929102726.2985188-1-john.g.garry@oracle.com> <20230929102726.2985188-2-john.g.garry@oracle.com> <20231109151013.GA32432@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Thu, Nov 09, 2023 at 05:01:10PM +0000, John Garry wrote: > Generally they come from the same device property. Then since > atomic_write_unit_max_bytes must be a power-of-2 (and > atomic_write_max_bytes may not be), they may be different. How much do we care about supporting the additional slack over the power of two version? > In addition, > atomic_write_unit_max_bytes is required to be limited by whatever is > guaranteed to be able to fit in a bio. The limit what fits into a bio is UINT_MAX, not sure that matters :) > atomic_write_max_bytes is really only relevant for merging writes. Maybe we > should not even expose via sysfs. Or we need to have a good separate discussion on even supporting any merges. Willy chimed in that supporting merges was intentional, but I'd really like to see numbers justifying it.