Thank you for the suggestion. Switching to virtio and/or e1000 helped but still was not able to exceed 450Mb/s. It took me awhile to figure out you had to either restart or reload libvirtd for the changes to take effect. Is there anything else I could check/change to approach 1000Mb/s or higher?

Thank you,

Bryan Coleman

"Daniel P. Berrange" <berrange@redhat.com>
Sent by: libvir-list-bounces@redhat.com

03/12/2009 09:42 AM

Please respond to
"Daniel P. Berrange" <berrange@redhat.com>

To	Bryan_Coleman@dart.biz
cc	libvir-list@redhat.com
Subject	Re: [libvirt] qemu-kvm networking speed

On Thu, Mar 12, 2009 at 09:28:56AM -0400, Bryan_Coleman@dart.biz wrote: > How do I change the networking speed provided to my qemu-kvm guest? I > have four gigabit ports bonded; however, my guest is showing just 100Mb/s. > I have used iperf to confirm. The reported 'speed' setting for emulated NICs is basically irrelevant since this is emulated hardware. The original real hardware may have been specced as 100mb/s, but that has no bearing on its speed in a virtual environment. The QEMU emulated devices will send/recv data until the hit a bottleneck, typically the CPU usage of the QEMU process is hit first. So you want a NIC that entails a low CPU overhead in QEMU. In order of prefernce you'll want to try virtio, e1000, rtl8139, ne2k_pci This can be set in libvirt xml with <model type='virtio'/> in the guest XML <interface> section. Obviously you need to adjust your guest OS to load correct drivers to match. Regards, Daniel -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :| -- Libvir-list mailing list Libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list