From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cc-smtpout3.netcologne.de ([89.1.8.213]:41715 "EHLO cc-smtpout3.netcologne.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932511AbcAZIy7 (ORCPT ); Tue, 26 Jan 2016 03:54:59 -0500 Subject: Re: btrfs-progs 4.4 re-balance of RAID6 is very slow / limited to one cpu core? To: Chris Murphy References: <56A230C3.3080100@netcologne.de> <56A6082C.3030007@netcologne.de> Cc: linux-btrfs From: Christian Rohmann Message-ID: <56A73460.7080100@netcologne.de> Date: Tue, 26 Jan 2016 09:54:56 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hey Chris and all, On 01/25/2016 11:13 PM, Chris Murphy wrote: > Does anyone suspect a kernel regression here? I wonder if its worth it > to suggest testing the current version of all fairly recent kernels: > 4.5.rc1, 4.4, 4.3.4, 4.2.8, 4.1.16? I think going farther back to > 3.18.x isn't worth it since that's before the major work since raid56 > was added. Quite a while ago I've done a raid56 rebuild and balance > that was pretty fast but it was only a 4 or 5 device test. Problem is that this balance did not work before going to 4.4 kernel, it's was simply crashing after about an hour or two of runtime. Currently I am using 4.4 kernel + btrfs-progs, so apart from 4.5rc1 I can not get any more bleeding edge. 4.5 I am happy to try, but not RC1 as there are already some bugs popping up regarding the BTRFS changes. On 01/26/2016 07:14 AM, Chris Murphy wrote: > Christian, what are you getting for 'iotop -d3 -o' or 'iostat -d3'. Is > it consistent or is it fluctuating all over the place? What sort of > eyeball avg/min/max are you getting? "1672.81 K/s 1672.81 K/s 0.00 % 6.99 % btrfs balance start -dstripes 1..11 -mstripes 1..11 " but it's jumping up to 25MB/s for a few polls, but most of the time it's at 1.3 to 1.7 MB/s You may check out more the various munin graphs of the box if you like: * http://mirror.netcologne.de/munin has all the goods. This also brings me to mention, that the disks (it's 12 disks though!) read somewhere between 20 and 60MB/s constantly. Regards Christian