From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: [RFC v1 0/5] VBD: enlarge max segment per request in blkfront Date: Wed, 19 Sep 2012 17:11:03 -0400 Message-ID: <20120919211103.GA9488@phenom.dumpdata.com> References: <20120907174922.GA13040@phenom.dumpdata.com> <5051A83B020000780009AF93@nat28.tlf.novell.com> <20120913132335.GD16635@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: "Duan, Ronghui" Cc: "'xen-devel@lists.xen.org'" , 'Ian Jackson' , 'Jan Beulich' , 'Stefano Stabellini' List-Id: xen-devel@lists.xenproject.org On Mon, Sep 17, 2012 at 06:33:29AM +0000, Duan, Ronghui wrote: > At last, I saw the regression in random io. > This is a patch to fix the performance regression. Original the pending request members are allocated from the stack, I alloc them when each request arrives in my last patch. But it will hurt performance. In this fix, I alloc all of them when blkback init. But due to some bugs there, we can't free it, the same to other pending requests member. I am looking for the reason. But have no idea for this now. > Konrad, thanks for your comments. Could you have a try when you have time. Sure. I get now: read : io=4096.0MB, bw=144258KB/s, iops=36064 , runt= 29075msec so much better I/O. > > > > > >> And with your patch got: > > > > > >> read : io=4096.0MB, bw=92606KB/s, iops=23151 , runt= > > > > > >> 45292msec > > > > > >> > > > > > >> without: > > > > > >> read : io=4096.0MB, bw=145187KB/s, iops=36296 , runt= > > > > > >> 28889msec