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 <[EMAIL PROTECTED]>
>
> 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.
-Andikkk
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
Please read the FAQ at http://www.tux.org/lkml/
