Re: [Xen-devel] Xen 4.3 development update

[Suravee Suthikulanit <suravee.suthikulpanit@xxxxxxx>]

On 4/2/2013 12:06 PM, Suravee Suthikulpanit wrote:
> On 4/2/2013 11:34 AM, Tim Deegan wrote:
> > At 16:42 +0100 on 02 Apr (1364920927), Jan Beulich wrote:
> > > > > > On 02.04.13 at 16:07, George Dunlap <George.Dunlap@xxxxxxxxxxxxx> 
> > > > > > wrote:
> > > > * AMD NPT performance regression after c/s 24770:7f79475d3de7
> > > >    owner: ?
> > > >    Reference: http://marc.info/?l=xen-devel&m=135075376805215
> > > This is supposedly fixed with the RTC changes Tim committed the
> > > other day. Suravee, is that correct?
> > This is a separate problem.  IIRC the AMD XP perf issue is caused by the
> > emulation of LAPIC TPR accesses slowing down with Andres's p2m locking
> > patches.  XP doesn't have 'lazy IRQL' or support for CR8, so it takes a
> > _lot_ of vmexits for IRQL reads and writes.
> Is there any tools or good ways to count the number of VMexit in Xen?
Tim/Jan,

I have used iperf benchmark to compare network performance (bandwidth) 
between the two versions of the hypervisor:
1. good: 24769:730f6ed72d70
2. bad: 24770:7f79475d3de7

In the "bad" case, I am seeing that the network bandwidth has dropped 
about 13-15%.
However, when I uses the xentrace utility to trace the number of VMEXIT, 
I actually see about 25% more number of VMEXIT in the good case.  This 
is inconsistent with the statement that Tim mentioned above.
Suravee

> Thanks,
> Suravee
> > Tim.


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