From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([59.151.112.132]:5992 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1750991AbbGaCet (ORCPT ); Thu, 30 Jul 2015 22:34:49 -0400 Subject: Re: mount btrfs takes 30 minutes, btrfs check runs out of memory To: John Ettedgui , , References: From: Qu Wenruo Message-ID: <55BADEC4.3020409@cn.fujitsu.com> Date: Fri, 31 Jul 2015 10:34:44 +0800 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: John Ettedgui wrote on 2015/07/29 18:55 +0000: > Hello, > I have the same issue and would like to add myself to this thread. > My btrfs partition is about 10tb on top of lvm2 and has been taking about a minute to mount in the past few months. > >> Qu Wenruo cn.fujitsu.com > writes: >> >> Quite common, especial when it grows large. >> But it would be much better to use ftrace to show which btrfs operation >> takes the most time. > > > I have got a trace file running this command: > trace-cmd record -e btrfs mount > > Since it is fairly big for an email I have gzipped it. > > Thanks! > John > Hi John, Thanks for the trace output. But it seems that, your root partition is also btrfs, causing a lot of btrfs trace from your systemd journal. Would you mind re-collecting the ftrace without such logging system caused btrfs trace? BTW, although I'm not quite familiar with ftrace, would you please consider collect ftrace with function_graph tracer? That would help a lot to find which takes the most time. But it may trace too much things and maybe hard to read. Thanks, Qu