On Mon, 25 Feb 2002, Michael Cohen wrote:
> This one was given to me by WLI himself;
Are you sure these are the latest bit-sparse primes ?
> +++ linux-patched/include/asm-alpha/param.h Mon Feb 25 20:44:35 2002
> +/* SPARSE_GOLDEN_RATIO_PRIME ought to be different for non-32bit arches. */
> +
> +#ifndef SPARSE_GOLDEN_RATIO_PRIME
> +#define SPARSE_GOLDEN_RATIO_PRIME 0x9e004001UL
> +#endif
> +++ linux-patched/include/asm-arm/param.h Mon Feb 25 20:43:13 2002
> +#ifndef SPARSE_GOLDEN_RATIO_PRIME
> +#define SPARSE_GOLDEN_RATIO_PRIME 0x9e004001UL
> +#endif
Yuck, the fact that you're defining the exact same constant in
many .h files is ugly. Could you move this to one place ?
(maybe linux/hash.h like Rusty is doing for 2.5?)
> + unsigned long hash;
> + hash = (unsigned long) mapping + index;
> + hash *= SPARSE_GOLDEN_RATIO_PRIME;
> + hash >>= BITS_PER_LONG - PAGE_HASH_BITS;
> + hash &= PAGE_HASH_SIZE - 1;
> + return hash;
For 64-bit systems you'll want:
1) a 64-bit golden ratio prime
2) expanding the bit ops by hand because gcc doesn't do
it for you
These last 2 points are easy, you can just copy the stuff
from the struct page patch I sent earlier.
cheers,
Rik
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This archive was generated by hypermail 2b29 : Thu Feb 28 2002 - 21:00:23 EST