From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Tso Subject: Re: ext4 unlink performance Date: Wed, 19 Nov 2008 16:18:40 -0500 Message-ID: <20081119211840.GA8021@mit.edu> References: <20081113185712.GB11204@untroubled.org> <20081113191000.GA11516@untroubled.org> <20081113204240.GF21652@mit.edu> <20081114041121.GB11746@untroubled.org> <20081114145914.GE25117@mit.edu> <20081115204423.GA4671@untroubled.org> <20081116005610.GI22948@mit.edu> <20081117004330.GC3436@webber.adilger.int> <20081119024021.GA10185@mit.edu> <20081119181000.GD3186@webber.adilger.int> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org To: Andreas Dilger Return-path: Received: from www.church-of-our-saviour.ORG ([69.25.196.31]:48434 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752743AbYKSVS5 (ORCPT ); Wed, 19 Nov 2008 16:18:57 -0500 Content-Disposition: inline In-Reply-To: <20081119181000.GD3186@webber.adilger.int> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, Nov 19, 2008 at 12:10:01PM -0600, Andreas Dilger wrote: > > That may be a side-effect of the mballoc per-CPU cache again, where > files being written in the same subdirectory are spread apart because > of the write thread being rescheduled to different cores. > It would be good for us to get confirmation one way or another about this theory. Bruce, if you have multiple CPU's (or cores on your system --- i.e., cat /proc/cpuinfo reports multiple processors), can you try unpacking your tarball on a test ext4 filesystem using something like: taskset 1 tar xjf /path/to/my/tarball.tar.bz2 The "taskset 1" will bind the tar process to only run on a single processors. If that significantly changes the time to do run rm -rf, can you save a raw e2image using that workload? That would be very useful indeed. Alternatively, if you don't have the taskset command handy, you can also add maxcpus=1 to the kernel boot command-line, which will force the system to only use one cpu. Using taskset is much more convenient, though. Thanks!! - Ted