On 22.03.2012 15:06, Anthony Bourguignon wrote: > Package: qemu-kvm > Version: 1.0+dfsg-9 > Severity: important > > Hello, > > I encountered an issue with version 1.0+dfsg-9 of qemu-kvm (it worked fine > with 1.0+dfsg-8). The network performances are really bad when I'm using > vhost and macvtap (bridge mode). Here is the cmdline launch by libvirt : > > /usr/bin/kvm -S -M pc-1.0 -enable-kvm -m 2048 -mem-prealloc -mem-path > /mnt/hugepages/libvirt/qemu -smp 2,sockets=2,cores=1,threads=1 -name test > -uuid 77f086e4-fec5-dc75-792b-4cfea46642ff -nodefconfig -nodefaults -chardev > socket,id=charmonitor,path=/var/lib/libvirt/qemu/test.monitor,server,nowait > -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown > -drive > file=/dev/vps/test,if=none,id=drive-virtio-disk0,format=raw,cache=none,aio=native > -device > virtio-blk-pci,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 > -netdev tap,fd=21,id=hostnet0,vhost=on,vhostfd=22 -device > virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:9a:c9:16,bus=pci.0,addr=0x3,bootindex=2 > -chardev pty,id=charserial0 -device > isa-serial,chardev=charserial0,id=serial0 -usb -vnc 0.0.0.0:0 -k fr -vga std > -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5 > > The vhost_net module is loaded on the host. On the guest side, downloads are > stalled at 15kb/s only. It works well if I'm using bridge interface instead > of macvtap, so it's not a problem with the host. If I revert the package to > version 1.0+dfsg-8, the guest interface is working at normal speed. > > Tell me if you need further investigations.
There was no network-related changes between -8 and -9. Macvtap performance has always been awful from the ground up, but this is due to kernel not qemu. Reportedly it become a bit better with latest kernels but I haven't checked. At any rate using macvtap isn't a good idea at this stage. /mjt -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
