Rik van Riel wrote:
Nick Piggin wrote:
We have percpu and cache affine page allocators, so when
userspace just frees a page, it is likely to be cache hot, so
we want to free it up so it can be reused by this CPU ASAP.
Likewise, when we newly allocate a page, we want it to be one
that is cache hot on this CPU.
Actually, isn't the clear page function capable of doing
some magic, when it writes all zeroes into the page, that
causes the zeroes to just live in CPU cache without the old
data ever being loaded from RAM?
That would sure be faster than touching RAM. Not sure if
we use/trigger that kind of magic, though :)
powerpc has and uses an instruction to zero a full cacheline, yes.
Not sure about x86-64 CPUs... I don't think they can do it.
--
SUSE Labs, Novell Inc.
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