Re: [PATCH] Update jhash.h with the new version of Jenkins' hash

[Ilpo Järvinen]

On Tue, 17 Feb 2009, Jozsef Kadlecsik wrote:

> On Thu, 12 Feb 2009, Rusty Russell wrote:
> 
> > My concern was that it's also bigger (and we inline it).  Performance is
> > pretty much a wash since we so rarely hash more than a few words.
> 
> In netfilter/conntrack (;-) we call the hash function for every packet, so 
> even if a small number of cycle can be gained at one lookup, I think it's 
> worth. And in the IPv4/IPv6 neutral nf_conntrack we hash 9 words.

FYI, I once looked into inlining cost and jhash functions were among the 
most wasteful (kernel-wide). Multiple jhash bodies were 100+ bytes, and 
the overall cost was 10k+. I never got to the final submit of the 
uninlining patch though...


-- 
 i.
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