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SubjectRe: DRM lock ordering fix series
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On Sat, 2009-03-28 at 01:58 +0100, Peter Zijlstra wrote:

> > OK. I'm not too excited here -- 10% of 2% of the CPU time doesn't get
> > me to the 10% loss that the slow path added up to. Most of the cost is
> > in k{un,}map_atomic of the returned pages.
>
> Also note that doing large gup() with gup_fast() will be undesirable due
> to it disabling IRQs. So iterating say several MB worth of pages will
> hurt like crazy. Currently all gup_fast() users do a single page lookup.

Also, what's this weird facination with 32bit, can you even buy a 32bit
only cpu these days?



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