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
