On Wed, Nov 21, 2012 at 03:00:25PM +0800, Asias He wrote: > On 11/21/2012 02:44 PM, Stefan Hajnoczi wrote: > > On Wed, Nov 21, 2012 at 7:42 AM, Asias He <as...@redhat.com> wrote: > >> On 11/21/2012 01:39 PM, Asias He wrote: > >>> On 11/20/2012 08:25 PM, Stefan Hajnoczi wrote: > >>>> On Tue, Nov 20, 2012 at 1:21 PM, Stefan Hajnoczi <stefa...@gmail.com> > >>>> wrote: > >>>>> On Tue, Nov 20, 2012 at 10:02 AM, Asias He <as...@redhat.com> 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 <k...@us.ibm.com> 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 <stefa...@redhat.com> > >>>>>> 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 > >> > >> Hi Stefan, > >> > >> If I enable the merge in guest the IOPS for seq read/write goes up to > >> ~400K/300K. If I disable the merge in guest the IOPS drops to ~17K/24K > >> for seq read/write (which is similar to the result I posted yesterday, > >> with merge disalbed). Could you please also share the numbers for rand > >> read and write in your setup? > > > > Thanks for running the test. Please send your rand read/write fio > > jobfile so I can run the exact same test. > > > > BTW I was running the default F18 (host) and RHEL 6.3 (guest) I/O > > schedulers in my test yesterday. > > Sure, this is the script I used to run the test in guest.
Thanks, will give this a try! Stefan