From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from magic.merlins.org ([209.81.13.136]:44621 "EHLO mail1.merlins.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753032AbaIPX5r (ORCPT ); Tue, 16 Sep 2014 19:57:47 -0400 Date: Tue, 16 Sep 2014 16:57:42 -0700 From: Marc MERLIN To: Filipe David Manana Cc: "linux-btrfs@vger.kernel.org" , Filipe David Borba Manana Subject: Re: btrfs differential receive has become excrutiatingly slow with COW files Message-ID: <20140916235742.GG8530@merlins.org> References: <20140908015124.GA21441@merlins.org> <20140915001836.GU8530@merlins.org> <20140915175747.GZ8530@merlins.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20140915175747.GZ8530@merlins.org> Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Mon, Sep 15, 2014 at 10:57:47AM -0700, Marc MERLIN wrote: > Unfortunately, due to my stupidity, the strace logging failed, but it looks > like I got about 12H worth of the following below. Interestingly that directory > is nocow (VM images). > Does btrfs send get unhappy with NOCOW? So I ran another differential send/receive last night and it took another 10 or 12H again. Strace shows most of the time was spent on my virtualbox images which did not change at all. The diff itself wasn't big and only took 2mn to generate: legolas:/mnt/btrfs_pool1# time btrfs send -p var_ggm_daily_ro.20140913_14:50:24 var_ggm_daily_ro.20140915_22:57:33 > /tmp/diff At subvol var_ggm_daily_ro.20140915_22:57:33 real 2m14.365s user 0m0.400s sys 1m10.192s legolas:/mnt/btrfs_pool1# du -sh /tmp/diff 11G /tmp/diff I have a filtered log showing any system call that took more than 1 sec, that list is small: http://marc.merlins.org/tmp/btrfs_receive.log Most of the time is apparently just death by a thousand cuts of many many system calls spent around receiving my virtual images that didn't change. Here's the full strace log if you wish http://marc.merlins.org/tmp/btrfs_receive.log.xz What do you think? Thanks, Marc -- "A mouse is a device used to point at the xterm you want to type in" - A.S.R. Microsoft is to operating systems .... .... what McDonalds is to gourmet cooking Home page: http://marc.merlins.org/ | PGP 1024R/763BE901