From: Eric Sandeen Subject: Re: EXT4 is ~2X as slow as XFS (593MB/s vs 304MB/s) for writes? Date: Mon, 01 Mar 2010 18:08:24 -0600 Message-ID: <4B8C56F8.70503@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, Alan Piszcz To: Justin Piszcz Return-path: Received: from mx1.redhat.com ([209.132.183.28]:11938 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753096Ab0CBAIa (ORCPT ); Mon, 1 Mar 2010 19:08:30 -0500 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: Justin Piszcz wrote: > Hello, > > Is it possible to 'optimize' ext4 so it is as fast as XFS for writes? > I see about half the performance as XFS for sequential writes. > > I have checked the doc and tried several options, a few of which are shown > below (I have also tried the commit/journal_async/etc options but none > of them get the write speeds anywhere near XFS)? > > Sure 'dd' is not a real benchmark, etc, etc, but with 10Gbps between 2 > hosts I get 550MiB/s+ on reads from EXT4 but only 100-200MiB/s write. > > When it was XFS I used to get 400-600MiB/s for writes for the same RAID > volume. > > How do I 'speed' up ext4? Is it possible? > FWIW I'm seeing similar things on fast storage (Fusion IO), though this is under 2.6.31. 500MB/s+ for xfs, 300 for ext4. Overwriting an existing file is no faster. I don't think this driver is blktraceable but I'll try a newer driver that should be I think. (xfs's overwrite went from 534 to 597 mb/s; ext4 sat at 320-ish) direct IO was good for both xfs & ext4 at around 530mb/s I'll see if I can get this running on a more recent kernel to do further investigation. -Eric