Re: [Xen-devel] Noticeably poor Intel GPU performance on 3.3 and 3.4 dom0 kernels

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Wed, May 30, 2012 at 12:14:07PM +0200, Joanna Rutkowska wrote:
> Hello,
> 
> I've recently been some newer Dom0 kernels (3.3.5, 3.4) under Xen 4.1.2,
> and have noticed that those kernel noticeably downgrade performance of
> (at least) Intel GPUs. This is easily noticeable even on such trivial
> tasks as scrolling a webpage in Firefox or Chrome. This slow GPU
> performance on 3.3 and 3.4 kernels is in stark contrast with what I see
> on 3.2.7 Dom0 kernel, where graphics works just great...
> 
> In order to make sure that this is not caused by power management set
> too strictly, I played with xenpm and made sure to set the following:

And are you building with CONFIG_INTEL_IOMMU=y?

> 1) xenpm set-scaling-governor performance
> 2) xenpm set-max-cstate 0
> 
> I have verified then that my processor: 1) keeps staying in P0 state
> (so, max frequency), and 2) keeps staying in C0 state.
> 
> Those setting didn't change anything regarding the poor graphics
> performance, though.
> 
> Any ideas what else I could test to find out the cause of this?
> 
> Thanks,
> joanna.
> 



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