2nd request -- Re: [Xen-users] QueryPerformaceCounter and TSC returns bad results with Windows HVM

[James Miller <jimm@xxxxxxxxxxxxxxx>]

James Miller wrote:
> 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
Hi everyone,

I hate to be a pest but this is becoming a _REAL_ show stopper for us 
going forward with using Xen.  I would appreciate any thoughts, if I'm 
asking in the wrong way or not providing enough info _PLEASE_ let me know.
About the only other thing I can offer is that the problem happens very 
infrequently but when it does the process will report, for example, that 
it went 2,451,046ms w/out talking to the server that's like ~40min 
meaning the QPC gave an erroneous response.  Almost as if a 64bit 
counter (I think it's a 64bit counter) was rolling over?.!
Anyway, thanks in advance for any suggestions or assistance

Jim




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