From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:60536) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tb30X-0004BP-Ae for qemu-devel@nongnu.org; Wed, 21 Nov 2012 00:37:58 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Tb30V-0005IX-Qw for qemu-devel@nongnu.org; Wed, 21 Nov 2012 00:37:57 -0500 Received: from mx1.redhat.com ([209.132.183.28]:5183) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tb30V-0005IL-Ii for qemu-devel@nongnu.org; Wed, 21 Nov 2012 00:37:55 -0500 Message-ID: <50AC691E.3090007@redhat.com> Date: Wed, 21 Nov 2012 13:39:42 +0800 From: Asias He MIME-Version: 1.0 References: <1352992746-8767-1-git-send-email-stefanha@redhat.com> <50AB470F.7050408@redhat.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 0/7] virtio: virtio-blk data plane List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: Kevin Wolf , Anthony Liguori , "Michael S. Tsirkin" , qemu-devel , Khoa Huynh , Stefan Hajnoczi , Paolo Bonzini On 11/20/2012 08:25 PM, Stefan Hajnoczi wrote: > On Tue, Nov 20, 2012 at 1:21 PM, Stefan Hajnoczi wrote: >> On Tue, Nov 20, 2012 at 10:02 AM, Asias He wrote: >>> Hello Stefan, >>> >>> On 11/15/2012 11:18 PM, Stefan Hajnoczi wrote: >>>> This series adds the -device virtio-blk-pci,x-data-plane=on property that >>>> enables a high performance I/O codepath. A dedicated thread is used to process >>>> virtio-blk requests outside the global mutex and without going through the QEMU >>>> block layer. >>>> >>>> Khoa Huynh reported an increase from 140,000 IOPS to 600,000 >>>> IOPS for a single VM using virtio-blk-data-plane in July: >>>> >>>> http://comments.gmane.org/gmane.comp.emulators.kvm.devel/94580 >>>> >>>> The virtio-blk-data-plane approach was originally presented at Linux Plumbers >>>> Conference 2010. The following slides contain a brief overview: >>>> >>>> http://linuxplumbersconf.org/2010/ocw/system/presentations/651/original/Optimizing_the_QEMU_Storage_Stack.pdf >>>> >>>> The basic approach is: >>>> 1. Each virtio-blk device has a thread dedicated to handling ioeventfd >>>> signalling when the guest kicks the virtqueue. >>>> 2. Requests are processed without going through the QEMU block layer using >>>> Linux AIO directly. >>>> 3. Completion interrupts are injected via irqfd from the dedicated thread. >>>> >>>> To try it out: >>>> >>>> qemu -drive if=none,id=drive0,cache=none,aio=native,format=raw,file=... >>>> -device virtio-blk-pci,drive=drive0,scsi=off,x-data-plane=on >>> >>> >>> Is this the latest dataplane bits: >>> (git://github.com/stefanha/qemu.git virtio-blk-data-plane) >>> >>> commit 7872075c24fa01c925d4f41faa9d04ce69bf5328 >>> Author: Stefan Hajnoczi >>> Date: Wed Nov 14 15:45:38 2012 +0100 >>> >>> virtio-blk: add x-data-plane=on|off performance feature >>> >>> >>> With this commit on a ramdisk based box, I am seeing about 10K IOPS with >>> x-data-plane on and 90K IOPS with x-data-plane off. >>> >>> Any ideas? >>> >>> Command line I used: >>> >>> IMG=/dev/ram0 >>> x86_64-softmmu/qemu-system-x86_64 \ >>> -drive file=/root/img/sid.img,if=ide \ >>> -drive file=${IMG},if=none,cache=none,aio=native,id=disk1 -device >>> virtio-blk-pci,x-data-plane=off,drive=disk1,scsi=off \ >>> -kernel $KERNEL -append "root=/dev/sdb1 console=tty0" \ >>> -L /tmp/qemu-dataplane/share/qemu/ -nographic -vnc :0 -enable-kvm -m >>> 2048 -smp 4 -cpu qemu64,+x2apic -M pc >> >> Was just about to send out the latest patch series which addresses >> review comments, so I have tested the latest code >> (61b70fef489ce51ecd18d69afb9622c110b9315c). > > Rebased onto qemu.git/master before sending out. The commit ID is now: > cf6ed6406543ecc43895012a9ac9665e3753d5e8 > > https://github.com/stefanha/qemu/commits/virtio-blk-data-plane > > Stefan Ok, thanks. /me trying -- Asias