From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: RE: experiences with raid5: stripe_queue patches Date: Tue, 16 Oct 2007 12:04:30 +1000 Message-ID: <18196.7214.82291.81090@notabene.brown> References: <200710151703.10404.bs@q-leap.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: =?gb2312?B?xe3Pr7q6?= Cc: Bernd Schubert , linux-raid@vger.kernel.org, dan.j.williams@intel.com List-Id: linux-raid.ids On Tuesday October 16, pengxihan@hotmail.com wrote: > In my opinion, one > of ways to increase raid5 performance may be to change STRIPE_SIZE to > to a bigger value. It is now equal to PAGE_SIZE. But we can't just > change it simply, some other codes must be modified. I havn't tried,:). > Maybe Neil can give us some advices! I really don't think increase STRIPE_SIZE would have much effect. You might save a bit of CPU (though it might cost you too) but it should change the order of requests, so it wouldn't affect disk io much. I really think this is a scheduling problem. We need to make sure to send the requests in the right order without delaying things needlessly, and avoid reads when ever possible. NeilBrown