Re: [Xen-devel] [Xen VGA Passthrough] Performance of AMD Radeon HD 6450 in Windows 7 HVM domU Poorer Than in Bare-Metal Windows 8.1 OS

[Gordan Bobic <gordan@xxxxxxxxxx>]

On 2014-09-09 17:51, Teo En Ming wrote:
> On 09/09/2014 23:49, Gordan Bobic wrote:
> > Also, how many VCPUs do you have in the domU vs. total in the
> > machine?
> I have 4 VCPUs in the domU and 4 cores in the machine.
A 25-40% drop from virtualization overheads isn't unheard of.
If some parts of the benchmark are CPU bound such a drop
wouldn't be particularly unusual.

> > Can you test bare metal with CPUs disabled? For example,
> > if you have a quad core CPU, disable 2 cores, test bare metal.
> How do I do that?
See if your BIOS has an option for it. I'm not sure if there
is a way to make Windows itself ignore some cores.

> > Then start up Xen, limit dom0 to 2 cores, give 2 cores to domU,
> > test and compare.
> 4 cores were automatically assigned to dom0. I gave 4 cores to domU as 
> well.
So limit dom0 to 2 cores, and give 2 cores to domU. Ideally pin
dom0 to the first 2 (0,1) and limit domU to the other 2 (2,3).



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel