From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from plane.gmane.org ([80.91.229.3]:55300 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031121Ab3HIVfw (ORCPT ); Fri, 9 Aug 2013 17:35:52 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1V7uLf-0002IZ-Kj for linux-btrfs@vger.kernel.org; Fri, 09 Aug 2013 23:35:51 +0200 Received: from dyndsl-080-228-178-103.ewe-ip-backbone.de ([80.228.178.103]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 09 Aug 2013 23:35:51 +0200 Received: from hurikhan77+btrfs by dyndsl-080-228-178-103.ewe-ip-backbone.de with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 09 Aug 2013 23:35:51 +0200 To: linux-btrfs@vger.kernel.org From: Kai Krakow Subject: Re: Why does btrfs benchmark so badly in this case? Date: Fri, 09 Aug 2013 23:35:33 +0200 Message-ID: <8u3gda-evs.ln1@hurikhan77.spdns.de> References: <20130808194015.GH16712@localhost.localdomain> <20130808203855.GI16712@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Sender: linux-btrfs-owner@vger.kernel.org List-ID: Josef Bacik schrieb: >> So I guess the reason that ZFS does well with that workload is that >> ZFS is using smaller blocks, maybe just 512B ? > > Yeah I'm not sure what ZFS does, but if you are writing over a block and > the size/offset isn't aligned then you'd see similar issues with ZFS since > it would > have to read+modify+write. It is likely that ZFS just is using a smaller > blocksize. >>From what I remember, ZFS uses dynamic block sizes. However, block size can be forced and thus tuned for workloads that require it: http://www.joyent.com/blog/bruning-questions-zfs-record-size Maybe that's the reason... It would be interesting to see how the benchmarks performed with forced block size. Regards, Kai