From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:47647 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757469AbbDVQzd (ORCPT ); Wed, 22 Apr 2015 12:55:33 -0400 Message-ID: <5537D27E.3080609@fb.com> Date: Wed, 22 Apr 2015 12:55:26 -0400 From: Chris Mason MIME-Version: 1.0 To: =?UTF-8?B?SG9sZ2VyIEhvZmZzdMOkdHRl?= , Subject: Re: [PATCH 0/4] btrfs: reduce block group cache writeout times during commit References: <1428954759-1304912-1-git-send-email-clm@fb.com> In-Reply-To: Content-Type: text/plain; charset="utf-8" Sender: linux-btrfs-owner@vger.kernel.org List-ID: 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. -chris