From: Christian Kujau Subject: Re: [Jfs-discussion] benchmark results Date: Fri, 25 Dec 2009 10:51:05 -0800 (PST) Message-ID: References: <19251.26403.762180.228181@tree.ty.sabi.co.uk> <20091224212756.GM21594@thunk.org> <20091225161453.GD32757@thunk.org> <20091225162238.GB19303@bitmover.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: tytso@mit.edu, jfs-discussion@lists.sourceforge.net, linux-nilfs@vger.kernel.org, xfs@oss.sgi.com, reiserfs-devel@vger.kernel.org, Peter Grandi , ext-users , linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org To: Larry McVoy Return-path: In-Reply-To: <20091225162238.GB19303@bitmover.com> Sender: reiserfs-devel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Fri, 25 Dec 2009 at 08:22, Larry McVoy wrote: > Dudes, sync() doesn't flush the fs cache, you have to unmount for that. Thanks Larry, that was exactly my point[0] too, I should add that to the results page to avoid further confusion or misassumptions: > Well, I do "sync" after each operation, so the data should be on > disk, but that doesn't mean it'll clear the filesystem buffers > - but this doesn't happen that often in the real world too. I realize however that on the same results page the bonnie++ tests were run with a filesize *specifically* set to not utilize the filesystem buffers any more but the measure *disk* performance while my "generic* tests do something else - and thus cannot be compared to the bonnie++ or hdparm results. > No idea if that is still supported, but sync() is a joke for benchmarking. I was using "sync" to make sure that the data "should" be on the disks now, I did not want to flush the filesystem buffers during the "generic" tests. Thanks, Christian. [0] http://www.spinics.net/lists/linux-ext4/msg16878.html -- BOFH excuse #210: We didn't pay the Internet bill and it's been cut off.