Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19

From: Nick Piggin
Date: Thu Nov 03 2005 - 20:20:19 EST


Linus Torvalds wrote:

On Fri, 4 Nov 2005, Nick Piggin wrote:

Looks like ppc64 is getting 64K page support, at which point higher
order allocations (eg. for stacks) basically disappear don't they?


Yes and no, HOWEVER, nobody sane will ever use 64kB pages on a general-purpose machine.

64kB pages are _only_ usable for databases, nothing else.

Why? Do the math. Try to cache the whole kernel source tree in 4kB pages vs 64kB pages. See how the memory usage goes up by a factor of _four_.


Yeah that's true. But Martin's worried about future machines
with massive memories - so maybe it is safe to assume those will
be using big pages, I don't know.

Maybe the solution is to bloat the kernel sources enough to make
64KB pages worthwhile?

--
SUSE Labs, Novell Inc.

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