Re: [boost] [hash] regular behaviour of hash function for double values

Subject: Re: [boost] [hash] regular behaviour of hash function for double values
From: Olaf van der Spek (ml_at_[hidden])
Date: 2012-01-31 10:12:35

On Tue, Jan 31, 2012 at 4:10 PM, Kai Schroeder
<kaischroeder3_at_[hidden]> wrote:
> Especially since some hash table implementations (e.g. intel's
> threading building blocks) only use the last few bits to determine the
> bucket, this can lead to very bad caching behaviour for the rather
> common case of regularly sampled points (equidistant samplings of
> power of 2 are e.g. common in computer graphics and numerical
> algorithms).
>
> Are you aware of this? Would you consider it a bug?

Yes, sounds like a bug in TBB. I don't think it's a good idea to discard bits.

Olaf