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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=ham 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 DCBF5C47083 for ; Thu, 3 Jun 2021 00:57:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BB525613E6 for ; Thu, 3 Jun 2021 00:57:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229620AbhFCA7C (ORCPT ); Wed, 2 Jun 2021 20:59:02 -0400 Received: from mail104.syd.optusnet.com.au ([211.29.132.246]:43177 "EHLO mail104.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229541AbhFCA7C (ORCPT ); Wed, 2 Jun 2021 20:59:02 -0400 Received: from dread.disaster.area (pa49-179-138-183.pa.nsw.optusnet.com.au [49.179.138.183]) by mail104.syd.optusnet.com.au (Postfix) with ESMTPS id 848A786182C; Thu, 3 Jun 2021 10:57:01 +1000 (AEST) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1lobfQ-008IZB-HZ; Thu, 03 Jun 2021 10:57:00 +1000 Date: Thu, 3 Jun 2021 10:57:00 +1000 From: Dave Chinner To: "Darrick J. Wong" Cc: linux-xfs@vger.kernel.org Subject: Re: [PATCH 39/39] xfs: expanding delayed logging design with background material Message-ID: <20210603005700.GC664593@dread.disaster.area> References: <20210519121317.585244-1-david@fromorbit.com> <20210519121317.585244-40-david@fromorbit.com> <20210527203844.GP2402049@locust> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210527203844.GP2402049@locust> X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.3 cv=YKPhNiOx c=1 sm=1 tr=0 a=MnllW2CieawZLw/OcHE/Ng==:117 a=MnllW2CieawZLw/OcHE/Ng==:17 a=kj9zAlcOel0A:10 a=r6YtysWOX24A:10 a=VwQbUJbxAAAA:8 a=7-415B0cAAAA:8 a=dR5lHU3L-_iKhazkLugA:9 a=CjuIK1q_8ugA:10 a=AjGcO6oz07-iQ99wixmX:22 a=biEYGPWJfzWAr4FL6Ov7:22 Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Thu, May 27, 2021 at 01:38:44PM -0700, Darrick J. Wong wrote: > On Wed, May 19, 2021 at 10:13:17PM +1000, Dave Chinner wrote: > > +As a result, permanent transactions only "regrant" reservation space during > > +xfs_trans_commit() calls, while the physical log space reservation - tracked by > > +the write head - is then reserved separately by a call to xfs_log_reserve() > > +after the commit completes. Once the commit completes, we can sleep waiting for > > +physical log space to be reserved from the write grant head, but only if one > > +critical rule has been observed:: > > + > > + Code using permanent reservations must always log the items they hold > > + locked across each transaction they roll in the chain. > > + > > +"Re-logging" the locked items on every transaction roll ensures that the items > > +the transaction chain is rolling are always relocated to the physical head of > > This reads (to me) a little awkwardly. One could ask if the transaction > chain itself is rolling the items? Which is not really what's > happening. How about: > > "...ensures that the items attached to the transaction chain being > rolled are always relocated..." Fixed. > > -This relogging is also used to implement long-running, multiple-commit > > -transactions. These transaction are known as rolling transactions, and require > > -a special log reservation known as a permanent transaction reservation. A > > -typical example of a rolling transaction is the removal of extents from an > > +A typical example of a rolling transaction is the removal of extents from an > > inode which can only be done at a rate of two extents per transaction because > > Ignoring rt files, do we even have /that/ limit anymore? Especially > considering the other patchset you just sent... :) Well.... Remind me to make this update in that patch set if I forget to do it. :P > With that one odd sentence up there reworked, > Reviewed-by: Darrick J. Wong Thx! -Dave. -- Dave Chinner david@fromorbit.com