From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f172.google.com ([209.85.212.172]:36185 "EHLO mail-wi0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965961AbbDWPml (ORCPT ); Thu, 23 Apr 2015 11:42:41 -0400 Received: by wizk4 with SMTP id k4so221011742wiz.1 for ; Thu, 23 Apr 2015 08:42:40 -0700 (PDT) Message-ID: <553912EF.7010004@gmail.com> Date: Thu, 23 Apr 2015 17:42:39 +0200 From: Marc Cousin MIME-Version: 1.0 To: dsterba@suse.cz, linux-btrfs@vger.kernel.org Subject: Re: snapshot destruction making IO extremely slow References: <550E7917.5030602@gmail.com> <20150325011937.GB20767@twin.jikos.cz> <55129428.7090508@gmail.com> <20150330142532.GI32051@suse.cz> <55196740.1000705@gmail.com> <20150331170516.GD6821@suse.cz> <5534CC2F.4080109@gmail.com> In-Reply-To: <5534CC2F.4080109@gmail.com> Content-Type: text/plain; charset=utf-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 20/04/2015 11:51, Marc Cousin wrote: > On 31/03/2015 19:05, David Sterba wrote: >> On Mon, Mar 30, 2015 at 05:09:52PM +0200, Marc Cousin wrote: >>>> So it would be good to sample the active threads and see where it's >>>> spending the time. It could be the somewhere in the rb-tree representing >>>> extents, but that's a guess. >>>> >>> I just need to be told how to do that :) >>> >>> Something like a perf top ? >> >> for i in `pgrep btrfs`; do >> ps $i >> sudo cat /proc/$i/stack 2>/dev/null >> done >> >> and capture samples every second. >> > > Sorry, it took me a while to reproduce this (I needed to be in front of the machine when it happens :) ) Hi, Anything more I can provide on this issue ? Regards