From mboxrd@z Thu Jan 1 00:00:00 1970 From: Asdo Subject: Re: xfs > md 50% write performance drop on .30+ kernel? Date: Tue, 13 Oct 2009 12:21:20 +0200 Message-ID: <4AD454A0.3050704@shiftmail.org> References: <66781b10910120958k4afb637ejba79e4c23900c4da@mail.gmail.com> <4AD3F64F.6070908@sauce.co.nz> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-reply-to: <4AD3F64F.6070908@sauce.co.nz> Sender: linux-raid-owner@vger.kernel.org To: Richard Scobie Cc: linux-raid List-Id: linux-raid.ids Richard Scobie wrote: > 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) > > > Richard Scobie wrote: > > Started testing a similar machine yesterday - 12GB RAM LSI SAS > > controller and 16 x WD RE3 1TB SATA md RAID6. > > > > With stripe cache set to 16384, I see dd writes of around 290MB/s and > > when bumped up to 32768 (the maximum), it increases to 407MB. > > An omission to the above - the machine is running > kernel-2.6.30.8-64.fc11.x86_64. That performance is amazing for me. With 2.6.31 kernel and stripe_cache_size 32768 I got around 185MB/sec dd writes (bs=1M) though xfs (or 400MB/sec dd to the device directly). My machine was a dual xeon 5430 and about 13 SATA Hitachi 7200 rpm disks, MD raid-5, chunk size 1MB, anticipatory scheduler, no LVM. The controller was a 3ware 9650-16ML . Do you think it was controller's overhead? I have heard mixed opinions about 3wares. What are the fastest controllers around for MD-raid use? Thank you