From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([222.73.24.84]:26259 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1750709Ab2JZEDQ (ORCPT ); Fri, 26 Oct 2012 00:03:16 -0400 Message-ID: <508A02BF.10502@cn.fujitsu.com> Date: Fri, 26 Oct 2012 11:25:51 +0800 From: Miao Xie Reply-To: miaox@cn.fujitsu.com MIME-Version: 1.0 To: Liu Bo CC: Linux Btrfs Subject: Re: [PATCH 0/3] flush delalloc by multi-task References: <5089045D.8050801@cn.fujitsu.com> <50892821.5010808@oracle.com> <5089EDB7.8030306@cn.fujitsu.com> <5089F003.8080400@oracle.com> In-Reply-To: <5089F003.8080400@oracle.com> Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Fri, 26 Oct 2012 10:05:55 +0800, Liu Bo wrote: > On 10/26/2012 09:56 AM, Miao Xie wrote: >>> I can see the potential improvements brought by flushing inodes this way. >>>> >>>> But I don't think it makes much sense by making waiting process multi-task, >>>> since even we spread wait order extents into different cpus, they just occpied >>>> the cpu and went on waiting and scheduled then, I mean, the bottleneck is on >>>> what we're waiting for. >> Thanks for your comment, I think only btrfs_run_ordered_operations(root, 0) needn't >> wait for the works, the others must wait. >> >> The first reason is to avoid changing the semantic of those tree function. The second >> reason is we have to wait for the completion of all works, if not, the file data in >> snapshots may be different with the source suvolumes because the flush may not end >> before the snapshot creation. >> > > Yes, it's right that they must wait for all workers to finish. > > But I don't mean that(sorry for my confusing words). > > IMO we don't need to let *btrfs_wait_ordered_extents()* run as multi-task. It also need to be done by multi-task because btrfs_wait_ordered_extents() doesn't imply that all the dirty pages in the ordered extent have been written into the disk, that is it also need do lots of things before waiting for the event - BTRFS_ORDERED_COMPLETE, so the multi-task process is useful, I think. Anyway, we need test to validate it. Thanks Miao > > thanks, > liubo > > > >