From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: I/O bandwidth control on KVM Date: Sat, 01 Mar 2008 22:18:03 -0600 Message-ID: <47CA2A7B.8000400@codemonkey.ws> References: <20080229.210531.226799765.ryov__28298.7898834564$1204287044$gmane$org@valinux.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel@lists.sourceforge.net, dm-devel@redhat.com, virtualization To: Ryo Tsuruta Return-path: In-Reply-To: <20080229.210531.226799765.ryov__28298.7898834564$1204287044$gmane$org@valinux.co.jp> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces@lists.sourceforge.net Errors-To: kvm-devel-bounces@lists.sourceforge.net List-Id: kvm.vger.kernel.org Hi Ryo, Ryo Tsuruta wrote: > Hello all, > > I've implemented a block device which throttles block I/O bandwidth, > which I called dm-ioband, and been trying to throttle I/O bandwidth on > KVM environment. But unfortunately it doesn't work well, the number of > issued I/Os is not according to the bandwidth setting. > On the other hand, I got the good result when accessing directly to > the local disk on the local machine. > > I'm not so familiar with KVM. Could anyone give me any advice? If you are using virtio drivers in the guest (which I presume you are given the reference to /dev/vda), try using the following -drive syntax: -drive file=/dev/mapper/ioband1,if=virtio,boot=on,cache=off This will force the use of O_DIRECT. By default, QEMU does not open with O_DIRECT so you'll see page cache effects. Regards, Anthony Liguori ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/