From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from plane.gmane.org ([80.91.229.3]:57152 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966204AbbDVQhr (ORCPT ); Wed, 22 Apr 2015 12:37:47 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1Ykxei-0003OP-Ms for linux-btrfs@vger.kernel.org; Wed, 22 Apr 2015 18:37:44 +0200 Received: from p4ff58343.dip0.t-ipconnect.de ([79.245.131.67]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 22 Apr 2015 18:37:44 +0200 Received: from holger.hoffstaette by p4ff58343.dip0.t-ipconnect.de with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 22 Apr 2015 18:37:44 +0200 To: linux-btrfs@vger.kernel.org From: Holger =?iso-8859-1?q?Hoffst=E4tte?= Subject: Re: [PATCH 0/4] btrfs: reduce block group cache writeout times during commit Date: Wed, 22 Apr 2015 16:37:38 +0000 (UTC) Message-ID: References: <1428954759-1304912-1-git-send-email-clm@fb.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: 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