On 04/05/2016 08:48 AM, Paolo Bonzini wrote:
I think it's fine to use the struct. The exact size of the struct
varies from 3 to 5 32-bit words, so it's hard to write nice
size-dependent code for the hash.
I don't think it is. We have 3 integers. It is trivial to create a simple
function of 2 multiplies, two adds, and a remainder.
Take the primes from the xxhash.h, for example:
(phys_pc * PRIME32_2 + pc * PRIME32_3 + flags)
% PRIME32_1
& (CODE_GEN_PHYS_HASH_SIZE - 1)
Obviously, some bucket measurements should be taken, but I can well imagine
that this might perform just as well as the fully generic hasher.
r~
