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Network performance regression with vde_switch
I've noticed a significant network performance regression when using vde_switch, starting about one week ago (10/05/2012); before that date, I used to get about 1.5 Gbits host to guest, but now I can only get about 320 Mbits; I didn't find any modification in net/vde.*, just in hw/virtio*.
My command line:
qemu-system-i386 -cdrom /bpd/bpd.iso -m 512 -boot d -enable-kvm \
-localtime -ctrl-grab -usbdevice tablet \
-device virtio-net-pci,mac=52:54:00:18:01:01,netdev=vde0,tx=bh,ioeventfd=on,x-txburst=32 \
-netdev vde,id=vde0 -vga std -tb-size 2M -cpu host -clock unix
My host runs a kernel 3.6.1 and my guest runs a kernel 3.5.4; the same problem happens with other host and guest versions, too.
I know there are better ways of running a guest, but using vde I get a cleaner environment in the host (just one tun/tap interface to manage...), which is quite good when running some accademic experiments.
Interestingly, at the same time I've noticed a performance enhancement of about 25~30 % when using a tun/tap interface, bridged or not.
Thank you, very much.
Edivaldo de Araujo Pereira
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