From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:30314 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965613AbbDWMwa (ORCPT ); Thu, 23 Apr 2015 08:52:30 -0400 Message-ID: <5538EB05.7050200@fb.com> Date: Thu, 23 Apr 2015 08:52:21 -0400 From: Chris Mason MIME-Version: 1.0 To: CC: =?UTF-8?B?SG9sZ2VyIEhvZmZzdMOkdHRl?= , "linux-btrfs@vger.kernel.org" Subject: Re: [PATCH 0/4] btrfs: reduce block group cache writeout times during commit References: <1428954759-1304912-1-git-send-email-clm@fb.com> <5537D27E.3080609@fb.com> In-Reply-To: Content-Type: text/plain; charset="utf-8" Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 04/23/2015 08:45 AM, Filipe David Manana wrote: > On Wed, Apr 22, 2015 at 5:55 PM, Chris Mason wrote: >> On 04/22/2015 12:37 PM, Holger Hoffstätte wrote: >>> On Wed, 22 Apr 2015 18:09:18 +0200, Lutz Vieweg wrote: >>> >>>> On 04/13/2015 09:52 PM, Chris Mason wrote: >>>>> Large filesystems with lots of block groups can suffer long stalls during >>>>> commit while we create and send down all of the block group caches. The >>>>> more blocks groups dirtied in a transaction, the longer these stalls can be. >>>>> Some workloads average 10 seconds per commit, but see peak times much higher. >>>> >>>> Since we see this problem very frequently on some shared development servers, >>>> I will try to install this ASAP. >>>> >>>> Meanwhile, can anybody already tell success stories about successfully removing >>>> lags by this patch? >>> >>> Works fine, but make sure to get the followup patch [1] as well while you're >>> at it. I've observed that my (bandwidth-throttled) backups now cause shorter, >>> nicely spaced-out blips of activity instead of longer ones when the writeback >>> kicks in. >>> >>> -h >>> >>> [1] https://git.kernel.org/cgit/linux/kernel/git/mason/linux-btrfs.git/commit/?h=integration-4.1&id=c1e31ffc317e4c28d242b1d961c9c6fe673c0377 >>> >> >> Great to hear. I recommend just using my for-linus-4.1 branch, since it >> has all the good things in one place. > > Trying the current integration-4.1 branch, I ran into the following > during xfstests/btrfs/049: > Ugh, I must not be waiting correctly in one of the inode cache writeout sections. But I've run 049 a whole bunch of times without triggering, can you get this to happen consistently? -chris