Re: test13-pre5

From: Andi Kleen (
Date: Thu Dec 28 2000 - 18:17:21 EST

On Thu, Dec 28, 2000 at 02:54:52PM -0800, David S. Miller wrote:
> Date: Thu, 28 Dec 2000 23:58:36 +0100
> From: Andi Kleen <>
> Why exactly a power of two ? To get rid of ->index ?
> To make things like "page - mem_map" et al. use shifts instead of
> expensive multiplies...

I thought that is what ->index is for ?

Also gcc seems to be already quite clever at dividing through small
integers, e.g. using mul and shift and sub, so it may not be even worth to reach
for a real power-of-two.

I suspect doing the arithmetics is at least faster than eating the
cache misses because of ->index.


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