On Fri, 28 Feb 2014 21:56:38 +0100
Peter Zijlstra <pet...@infradead.org> wrote:
> Like already said; _trace is an absolutely abysmal name. Also you
> _really_ don't want an unconditional CR2 write in there, that's just
> stupidly expensive.
But a read isn't. Which is why we only do a write if the copy caused a
page fault (which is already expensive).
The proposed patch will have:
if (cr2 != read_cr2())
write_cr2(cr2);
>
> Also, this function is called a _LOT_ under certain workloads, I don't
> know how cheap a CR2 read is, but it had better be really cheap.
That's a HPA question.
-- Steve
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