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 X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B5001C433E0 for ; Thu, 25 Feb 2021 08:37:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 67B6664ED3 for ; Thu, 25 Feb 2021 08:37:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235859AbhBYIhz (ORCPT ); Thu, 25 Feb 2021 03:37:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34580 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233814AbhBYIhy (ORCPT ); Thu, 25 Feb 2021 03:37:54 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 83BEFC061574 for ; Thu, 25 Feb 2021 00:37:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; 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=3l8kxor38nJYLXJSvNiz3pqieSlDVvuFpCyM5tkLzSA=; b=gLd+Rkr5zxPEN2jMzDwWA6B9Vb DTWJi7O+1OEI137dsOL/AT0nOM3jg9gchaCRLwvN9+1ubFp6WTTW60utcsHhwoYayhI5uqxuQ2/8M c20yjq7Dk62r/FO6PZgOy0eEDH4TaxGWC399nF8bA8BKbnBbqEWxVXnqR8sXEvAN2O6miKMV9II1R DYEJOqCciyEuMn2glKLPpxAy4qti06LNiEPzrJYfvPF9uF0F2epgR5M6EzJ8uaPsoLV429eZCU4Tz nWyVK28JyzSln9tGBb2mKX1+FUBR2uoY0RwkRFXyisWyBljvHUpIfrdpaXO+izneiQR685yvA4URp hu/mOkGA==; Received: from 213-225-9-156.nat.highway.a1.net ([213.225.9.156] helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lFC8p-00ATTd-9D; Thu, 25 Feb 2021 08:37:02 +0000 Date: Thu, 25 Feb 2021 09:34:47 +0100 From: Christoph Hellwig To: Dave Chinner Cc: "Darrick J. Wong" , linux-xfs@vger.kernel.org Subject: Re: [PATCH 2/8] xfs: separate CIL commit record IO Message-ID: References: <20210223033442.3267258-1-david@fromorbit.com> <20210223033442.3267258-3-david@fromorbit.com> <20210224203429.GR7272@magnolia> <20210224214417.GB4662@dread.disaster.area> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210224214417.GB4662@dread.disaster.area> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Thu, Feb 25, 2021 at 08:44:17AM +1100, Dave Chinner wrote: > > Also, do you have any idea what was Christoph talking about wrt devices > > with no-op flushes the last time this patch was posted? This change > > seems straightforward to me (assuming the answers to my two question are > > 'yes') but I didn't grok what subtlety he was alluding to...? > > He was wondering what devices benefited from this. It has no impact > on highspeed devices that do not require flushes/FUA (e.g. high end > intel optane SSDs) but those are not the devices this change is > aimed at. There are no regressions on these high end devices, > either, so they are largely irrelevant to the patch and what it > targets... I don't think it is that simple. Pretty much every device aimed at enterprise use does not enable a volatile write cache by default. That also includes hard drives, arrays and NAND based SSDs. Especially for hard drives (or slower arrays) the actual I/O wait might matter. What is the argument against making this conditional?