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My setup:

  • Proxmox on the host machine with vmbr0 bridge for guests and a shorewall firewall
  • Guests (both KVM not openvz):
    • Windows Server '08
    • Debian lenny

I can download a speed test file on the proxmox host (wget) and on the windows server (firefox) with about 8-10MB/s. But when I download the file with wget on the debian guest it's only 2-3MB/s. Both guests use the same network bridge, both have 'rtl8139' as the network card in KVM.

Someone knows how to fix that? I want to use the debian VM as a webserver so it needs some bandwidth.

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2 Answers 2

up vote 0 down vote accepted

If you use kvm you should:

  • disable the io scheduler with bootstring elevator=none
  • use virtio net drivers
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agreed on the virtio drivers. the scheduler I prefer for hosts is deadline though

Besides that, have you checked with tcpdump what is going on underneath the hood?

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deadline is a good guess for the kvm server - but it does not make sense to have a scheduler in the server and in all guests... –  Andreas Rehm Sep 10 '10 at 11:58
    
yeah, the guests don't need it. I haven't seen cfq get in the way though, and I have lots of guests on KVM –  dyasny Sep 10 '10 at 12:09

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