EXA for radeon experimental patch
jbarnes at virtuousgeek.org
Thu Sep 1 13:35:10 PDT 2005
On Thursday, September 1, 2005 11:59 am, Eric Anholt wrote:
> > Why this? The kernel has support for paging, so it could easily free
> > up some continuous pages just by swapping them out if they are used.
> It would be nice if it were true. But getting physically contiguous
> pages any time after boot (of any significant size) is hard. I'm
> guessing due to wired pages being sprinkled around?
Yep. Over time, the kernel will allocate non-pageable memory all over
the system, which makes getting contiguous regions after a few hours of
uptime pretty difficult or impossible. There is some work underway to
mitigate that a bit, but it's not upstream yet. And even if it was, we
probably shouldn't count on it since it still won't *guarantee* that we
get big contiguous chunks when we ask for them (the only way to do that
would involve unacceptable performance losses on many platforms).
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