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[Xen-users] QueryPerformaceCounter and TSC returns bad results with Wind

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] QueryPerformaceCounter and TSC returns bad results with Windows HVM
From: James Miller <jimm@xxxxxxxxxxxxxxx>
Date: Wed, 15 Oct 2008 15:20:30 -0500
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Hi everyone,

We have a server with 2 sockets, 4 cores each, running CentOS release 5 (Final) and Xen 3.0.3. On that server we have 7 Windows 2003 DomUs. We've locked each one to a specific core and each has a single CPU HAL. We have an application which uses QueryPerformanceCounter. On very rare occasions a call to QPC returns a bad result causing our processes to disconnect from the server.
I've read about some bugs with HPC
http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=1291
I've also read something about not using APCI somewhat mitigates this issue.

Could someone tell me if this issues is being or has been resolved by later versions of Xen?

I have, below, a sample configuration of a Windows HVM DomU as well as the output of xm vcpu-list. Please let me know if there is any additional information I can provide to help resolve this issue and I greatly appreciate all your help.


Sample config
import os, re
arch = os.uname()[4]
if re.search('64', arch):
   arch_libdir = 'lib64'
else:
   arch_libdir = 'lib'
name = 'evalvm01.vm'
kernel = '/usr/lib/xen/boot/hvmloader'
builder='hvm'
boot='c'
memory = 2048
vif = [ 'type=ioemu, vifname=vifevalvm01, mac=aa:00:ef:39:a0:08 ,bridge=xenbr1' ]
device_model = '/usr/' + arch_libdir + '/xen/bin/qemu-dm'
vnc=1
sdl=0
vcpus = 1
cpus ="1"
vnclisten='0.0.0.0'
vncpasswd='xxxxxxxxxx'
disk = [ 'phy:/dev/vg01/evalvm01,ioemu:hda,w']
acpi=1
vncunused=1
vncdisplay=1

xm vcpu-list
Name ID VCPUs CPU State Time(s) CPU Affinity
Domain-0                           0     0     0   r--  2794806.2 0
Domain-0                           0     1     -   --p       2.0 any cpu
Domain-0                           0     2     -   --p       1.1 any cpu
Domain-0                           0     3     -   --p       1.4 any cpu
Domain-0                           0     4     -   --p       0.9 any cpu
Domain-0                           0     5     -   --p       0.9 any cpu
Domain-0                           0     6     -   --p       0.8 any cpu
Domain-0                           0     7     -   --p       0.9 any cpu
evalvm01.vm                      118     0     1   -b-   27903.4 1
evalvm02.vm                      112     0     2   -b-   10507.8 2
evalvm03.vm                      113     0     3   -b-    2445.3 3
evalvm04.vm                      116     0     4   -b-   79872.1 4
evalvm05.vm                      119     0     5   -b-   38717.1 5
evalvm06.vm                      115     0     6   -b-   98750.3 6
evalvm07.vm                      117     0     7   r--   65222.2 7


Jim


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