From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp1040.oracle.com ([156.151.31.81]:32492 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751349Ab2JZCF6 (ORCPT ); Thu, 25 Oct 2012 22:05:58 -0400 Message-ID: <5089F003.8080400@oracle.com> Date: Fri, 26 Oct 2012 10:05:55 +0800 From: Liu Bo MIME-Version: 1.0 To: miaox@cn.fujitsu.com 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> In-Reply-To: <5089EDB7.8030306@cn.fujitsu.com> Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: 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. thanks, liubo