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 04:57:00PM +0200, Marek Marczykowski wrote:
> On 30.05.2012 16:28, Konrad Rzeszutek Wilk wrote:
> > 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?
> 
> Yes:
> CONFIG_GART_IOMMU=y
> # CONFIG_CALGARY_IOMMU is not set
> CONFIG_SWIOTLB=y
> CONFIG_IOMMU_HELPER=y
> (...)
> CONFIG_IOMMU_API=y
> CONFIG_IOMMU_SUPPORT=y
> CONFIG_AMD_IOMMU=y
> # CONFIG_AMD_IOMMU_STATS is not set
> CONFIG_AMD_IOMMU_V2=m
> CONFIG_DMAR_TABLE=y
> CONFIG_INTEL_IOMMU=y
> CONFIG_INTEL_IOMMU_DEFAULT_ON=y
> CONFIG_INTEL_IOMMU_FLOPPY_WA=y
> CONFIG_IRQ_REMAP=y

In that case I think you might need to do some git bisection to figure
out which patch caused the slow-down. Are there any obvious things in the
kernel logs (you might have to boot it with loglevel=8 debug)?

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