Ying-Shiuan Pan, Thanks again - please see few questions below. Regards, Barak
On Tue, Jan 14, 2014 at 5:37 AM, Ying-Shiuan Pan <yingshiuan....@gmail.com>wrote: > Hi, Barak, > > Hope the following info can help you > > 1. > HOST: > <http://git.linaro.org/people/christoffer.dall/linux-kvm-arm.git> > http://git.linaro.org/people/christoffer.dall/linux-kvm-arm.git > branch: v3.10-arndale > config: arch/arm/configs/exynos5_arndale_defconfig > dtb: arch/arm/boot/dts/exynos5250-arndale.dtb > rootfs: Ubuntu 13.10 > > GUEST: > Official 3.12 > config: arch/arm/configs/vexpress_defconfig with virtio-devices enabled > dtb: arch/arm/boot/dts/vexpress-v2p-ca15-tc1.dtb > rootfs: Ubuntu 12.04 > > 2. > We are still developing it in progress and will try to open source asap. > The main purpose of that patch is to introduce the ioeventfd into kvm-arm > [Barak] Do you have any estimation about when you can release these patches? [Barak] Is this required for enabling vhost-net? > > 3. as mentioned in 1. > > 4. qemu-1.6.0 > > 5. We ported part of guest/host notifiers of virtio-pci to virtio-mmio > [Barak] Any patches available for this? [Barak] Is this required for enabling vhost-net? > > 6. /usr/bin/qemu-system-arm -enable-kvm -kernel /root/nfs/zImage -m 128 > --machine vexpress-a15 -cpu cortex-a15 -drive > file=/root/nfs/guest-1G-precise-vm1.img,id=virtio-blk,if=none,cache=none > -device virtio-blk-device,drive=virtio-blk -append "earlyprintk=ttyAMA0 > console=ttyAMA0 root=/dev/vda rw > ip=192.168.101.101::192.168.101.1:vm1:eth0:off > --no-log" -dtb /root/nfs/vexpress-v2p-ca15-tc1.dtb --nographic -chardev > socket,id=mon,path=/root/vm1.monitor,server,nowait -mon > chardev=mon,id=monitor,mode=readline -device > virtio-net-device,netdev=net0,mac="52:54:00:12:34:01" -netdev > type=tap,id=net0,script=/root/nfs/net.sh,downscript=no,vhost=off > [Barak] Could you share "/root/nfs/net.sh" with me? [Barak] In the guest i can see that eth0 has all offload features disabled and cannot be enabled. I suspect this is related to the tap configuration in the host. Do you have any ideas? > > vhost-net could be truned on by changing the last parameter vhost=on. > [Barak] When enabling vhost i get errors in qemu, do you know what might be the reason? [Barak] qemu-system-arm: binding does not support guest notifiers [Barak] qemu-system-arm: unable to start vhost net: 38: falling back on userspace virtio > > > -- > Ying-Shiuan Pan, > H Div., CCMA, ITRI, TW > > > ---- > Best Regards, > 潘穎軒Ying-Shiuan Pan > > > 2014/1/13 Barak Wasserstrom <wba...@gmail.com> > >> Ying-Shiuan Pan, >> Your experiments with arndale Exynos-5250 board can help me greatly and >> i would really appreciate if you share with me the following information: >> 1. Which Linux kernel did you use for the host and for the guest? >> 2. Which Linux kernel patches did you use for KVM? >> 3. Which config files did you use for both the host and guest? >> 4. Which QEMU did you use? >> 5. Which QEMU patches did you use? >> 6. What is the exact command line you used for invoking the guest, with >> and without vhost-net? >> >> Many thanks in advance! >> >> Regards, >> Barak >> >> >> >> On Mon, Jan 13, 2014 at 5:47 AM, Ying-Shiuan Pan < >> yingshiuan....@gmail.com> wrote: >> >>> Hi, Barak, >>> >>> We've tried vhost-net in kvm-arm on arndale Exynos-5250 board (it >>> requires some patches in qemu and kvm, of course). It works (without irqfd >>> support), however, the performance does not increase much. The throughput >>> (iperf) of virtio-net and vhost-net are 93.5Mbps and 93.6Mbps respectively. >>> I thought the result are because both virtio-net and vhost-net almost >>> reached the limitation of 100Mbps Ethernet. >>> >>> The good news is that we even ported vhost-net in our kvm-a9 hypervisor >>> (refer: >>> http://academic.odysci.com/article/1010113020064758/evaluation-of-a-server-grade-software-only-arm-hypervisor), >>> and the throughput of vhost-net on that platform (with 1Gbps Ethernet) >>> increased from 323Mbps to 435Mbps. >>> >>> -- >>> Ying-Shiuan Pan, >>> H Div., CCMA, ITRI, TW >>> >>> >>> ---- >>> Best Regards, >>> 潘穎軒Ying-Shiuan Pan >>> >>> >>> 2014/1/13 Peter Maydell <peter.mayd...@linaro.org> >>> >>>> On 12 January 2014 21:49, Barak Wasserstrom <wba...@gmail.com> wrote: >>>> > Thanks - I got virtio-net-device running now, but performance is >>>> terrible. >>>> > When i look at the guest's ethernet interface features (ethtool -k >>>> eth0) i >>>> > see all offload features are disabled. >>>> > I'm using a virtual tap on the host (tap0 bridged to eth3). >>>> > On the tap i also see all offload features are disabled, while on br0 >>>> and >>>> > eth3 i see the expected offload features. >>>> > Can this explain the terrible performance i'm facing? >>>> > If so, how can this be changed? >>>> > If not, what else can cause such bad performance? >>>> > Do you know if vhost_net can be used on ARM Cortex A15 host/guest, >>>> even >>>> > though the guest doesn't support PCI & MSIX? >>>> >>>> I have no idea, I'm afraid. I don't have enough time available to >>>> investigate performance issues at the moment; if you find anything >>>> specific you can submit patches... >>>> >>>> thanks >>>> -- PMM >>>> >>>> >>> >> >
