Marcelo Tosatti wrote:
On Tue, Jan 20, 2009 at 03:53:06PM +0100, Sven Rudolph wrote:
Hello,
first the facts required by bug reporting guidelines:
- two Quad-Core AMD Opteron(tm) Processors 2352
- kvm-83 (both kernel and userland)
- Host kernel: 2.6.28.1, x86_64
- guest:
- 4 CPUs assigned to this guest (-smp 4)
- Microsoft Windows 2003 Server, Standard Edition, Service Pack 2
- qemu command line:
qemu-system-x86_64 -m 4096 -boot c -hda hda.dat -smp 4 \
-net nic,macaddr=00:50:56:24:0b:37,model=virtio \
-net tap,ifname=vm03,script=no,downscript=no
The problem: When running "ping -n 3 localhost" on the guest it should
wait one second between each ping request and the time needed should
be non-negative and below 10 ms. Instead, ping does not actually wait
between sending the packets, and the time for the requests ist often
displayed to be too large or negative. Simple examples:
[WinNT] ping -n 3 localhost
Ping wird ausgefhrt fr localhost [127.0.0.1] mit 32 Bytes Daten:
Antwort von 127.0.0.1: Bytes=32 Zeit=-465ms TTL=128
Antwort von 127.0.0.1: Bytes=32 Zeit=-613ms TTL=128
Antwort von 127.0.0.1: Bytes=32 Zeit=-465ms TTL=128
Sven, Dor,
Can you try to use the AMD CPU drivers for Windows?
Take a look at http://forums.citrix.com/thread.jspa?threadID=93813
http://www.therightstuff.de/2007/06/05/The-Case-Of-The-Negative-Ping.aspx
I don't doubt the KVM tsc syncing code for AMD is not involved, though.
Installing AMD's driver for powerNow solves this issue.
Joerg, can you please supply us some explanations?
Thanks,
Dor
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