Messages in this thread | | | Date | Mon, 25 Feb 2002 21:10:34 -0500 | From | Michael Cohen <> | Subject | Re: Submssions for 2.4.19-pre [Fibonacci Hashing (William Lee Irwin)] [Discuss :) ] |
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On Mon, 25 Feb 2002 23:04:58 -0300 (BRT) Rik van Riel <riel@conectiva.com.br> wrote:
> 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 ?
WLI has yet to update me, and I've yet to see anything new from him in this area. I could be mistaken.
> > +++ 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?)
Possible. Take a look at HZ though. It's an arch-specific parameter similar to HZ (different for some arches, but not all) and it looks like it belongs in params.h for that reason.
> > + 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.
Great, thanks :)
> cheers, > > Rik > -- > "Linux holds advantages over the single-vendor commercial OS" > -- Microsoft's "Competing with Linux" document > > http://www.surriel.com/ http://distro.conectiva.com/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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