From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [Bug 18632] "INFO: task" dpkg "blocked for more than 120 seconds. Date: Thu, 9 Jun 2011 07:02:14 -0400 Message-ID: <20110609110214.GA9017@infradead.org> References: <201106082138.p58Lchgj002615@demeter2.kernel.org> <20110608150241.8412a63d.akpm@linux-foundation.org> <20110609033217.GA10741@localhost> <20110609035426.GA12061@localhost> <20110609082718.GA10335@infradead.org> <20110609090906.GA19186@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Christoph Hellwig , Dave Chinner , Andrew Morton , Jan Kara , "linux-fsdevel@vger.kernel.org" , "bugzilla-daemon@bugzilla.kernel.org" , "daaugusto@gmail.com" , "kernel-bugzilla@cygnusx-1.org" , "listposter@gmail.com" , "justincase@yopmail.com" , "clopez@igalia.com" To: Wu Fengguang Return-path: Received: from 173-166-109-252-newengland.hfc.comcastbusiness.net ([173.166.109.252]:44549 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754720Ab1FILCY (ORCPT ); Thu, 9 Jun 2011 07:02:24 -0400 Content-Disposition: inline In-Reply-To: <20110609090906.GA19186@localhost> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Thu, Jun 09, 2011 at 05:09:06PM +0800, Wu Fengguang wrote: > I have a sync livelock test script and it sometimes livelocked on XFS > even with the livelock fix patches. Ext4 is always OK. This sounds similar to the cfq issue just posted to lkml as "CFQ: async queue blocks the whole system". Does this happen with non-CFQ I/O schedulers, too? > [ 3581.185120] [] xfs_ioend_wait+0x87/0x9f This waits for the I/O completion to actually arrive - something that XFS does correctly in both sync and fsync, but ext4 only does for fsync. It might have some issues in the way it's implemented, I'll look if we can do something. But I suspect cfq delaying async writes too much is definitively going to cause issues for us here.