Re: CPU consumption is going as high as 95% on ARM Cortex A8

[Russell King - ARM Linux <linux@arm.linux.org.uk>]

On Mon, Dec 21, 2009 at 11:56:23AM +0530, Hiremath, Vaibhav wrote:
> >         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
> > 
> > will result in the memory being mapped as 'Strongly Ordered',
> > resulting
> > in there being multiple mappings with differing types.  In later
> > kernels, we have pgprot_dmacoherent() and I'd suggest changing the
> > above
> > macro for that.
> > 
> 
> I tried with your suggestion above but unfortunately it didn't work for
> me. I am seeing the same behavior with the pgprot_dmacoherent(). I
> pulled your patch (which got applied cleanly on 2.6.32-rc5) -

What happens if you comment out the pgprot_dmacoherent() / pgprot_noncached()
line completely?

I suspect that will "solve" the problem - but you'll then no longer have
DMA coherency with userspace, so its not really a solution.

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