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SubjectRe: test13-pre5
On Thu, 28 Dec 2000, Andi Kleen wrote:
> On Thu, Dec 28, 2000 at 02:33:07PM -0800, David S. Miller wrote:
> > Date: Thu, 28 Dec 2000 23:17:22 +0100
> > From: Andi Kleen <ak@suse.de>
> >
> > Would you consider patches for any of these points?
> >
> > To me it seems just as important to make sure struct page is
> > a power of 2 in size, with the waitq debugging turned off this
> > is true for both 32-bit and 64-bit hosts last time I checked.
>
> Why exactly a power of two ? To get rid of ->index ?

Most likely to minimise the number of cache misses needed
to access a complete page_struct.

Then again, I guess 48 bytes would _also_ guarantee that
we never need more than 2 cache misses to access every
part of the page_struct.

And the memory wasted in the page_struct may well be a
bigger factor than the cache misses on lots of systems...

(time for another CONFIG option? ;))

regards,

Rik
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