From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: xfs > md 50% write performance drop on .30+ kernel? Date: Mon, 12 Oct 2009 21:33:52 -0400 Message-ID: <20091013013352.GA24869@infradead.org> References: <66781b10910120958k4afb637ejba79e4c23900c4da@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <66781b10910120958k4afb637ejba79e4c23900c4da@mail.gmail.com> Sender: linux-raid-owner@vger.kernel.org To: mark delfman Cc: Linux RAID Mailing List List-Id: linux-raid.ids On Mon, Oct 12, 2009 at 05:58:20PM +0100, mark delfman wrote: > Hi... in recent tests we are seeing a 50% drop in performance from > XFS>MD on a 2.6.30 kernel (compared to a 2.6.28 kernel) > > In short: Performance to MD0 direct = circa 1.7GBsec (see below), via > xfs circa 850MBsec. On previous system (2.6.28) there was no drop in > performance (in fact often an increase). > > I am hopefully that this is simply a matter of barriers etc on the > newer kernel and MD, but we have tried many options and nothing seems > to change this so would very much appreciate advice. Did barrier support for RAID0 got introduced in 2.6.30?