RE: [Xen-devel] System time monotonicity

["Ian Pratt" <Ian.Pratt@xxxxxxxxxxxx>]

> > Some instrumentation indicated that we had cross-VCPU jitter of 
> > significant deltas, ~18us at worst. Though the 
> instrumentation wasn't 
> > completely reliable so that might not be accurate.
> 
> I've done some more testing, the problem appears to be 
> significantly worse than you're claiming. I store the 
> previously read value in the thread structure and breakpoint 
> whenever it fails:

Try booting with one physical (maxcpus=1 on the xen command line) CPU
just to verify this isn't a multi-CPU issue.

If you're still seeing jitter, please post the boot logs.

We've seen this on white-box AMD systems which were over heating and the
CPU was bouncing in and out of thermal throttling, but never on a tier-1
vendor system.

You could try switching between the PIT and HPET as the calibration
source. 

Ian


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel