---- Best Regards, 潘穎軒Ying-Shiuan Pan
2014/1/14 Barak Wasserstrom <wba...@gmail.com> > 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? > Actually, No. I will discuss with my boss about the release plan. > [Barak] Is this required for enabling vhost-net? > Yes, it is because vhost-net relies on ioeventfd to get kick request from front-end driver. > >> >> 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? > I did not see any.. but there might be somebody is also developing this.. > [Barak] Is this required for enabling vhost-net? > Yes. Without those notifiers, you will see the error messages as you mentioned below. > > >> >> 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? > Sorry, I forgot that. --------------- #!/bin/sh ifconfig $1 0.0.0.0 brctl addif virbr0 $1 --------------- virbr0 is a bridge created by manual. The setup steps of virbr0 are also provided: brctl create virbr0 brctl addif virbr0 eth0 ifconfig virbr0 [ETH0_IP] ifconfig eth0 0.0.0.0 [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 > QEMU requires host/guest notifiers to setup vhost-net, but currently virtio-mmio does not support yet. That's why you got those error messages. > > >> >> >> -- >> 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 >>>>> >>>>> >>>> >>> >> >
