Re: [boost] [bloom] Benchmarks with Knuth multiplier-based hash production

On 12 Jun 2025, at 21:56, Joaquin M López Muñoz via Boost <boost@lists.boost.org> wrote:

For branchful lookup, a cost model for mixed lookup would be

P*M*(A*K) + (1-P)*M*C

where P is the percentange of successful lookups and M is an extra cost factor on top of the non-mixed approach due to branch mispredictions.

I agree this effect will affect measurements to the point that you will never be able to be 100% sure. Lets just agree on the obvious consensus: an extra 64bit multiplication cannot affect the running time of any program on modern CPUs. The multiplier is from THE ART OF COMPUTER PROGRAMMING by D. Knuth, volume II, page 108. Regards, Kostas