IP Upstream Hash

[chateau Xiao]

do you mean, in the next version, murmur2 hash function will be used in
nginx?

and do you show the benchmark between the orignial algorithm and the new
one?

On Thu, Jul 21, 2011 at 5:43 PM, Igor Sysoev <igor at sysoev.ru> wrote:

> On Wed, Jul 20, 2011 at 02:18:52PM -0700, Matthieu Tourne wrote:
> > Hi all,
> >
> > I was looking at the code in ngx_http_upstream_ip_hash_module.c
> > And I'm not sure where the hashing algorithm for IPs is coming from,
> > especially those lines :
> >
> >             iphp->hash = 89;
> >
> >             hash = (hash * 113 + iphp->addr[i]) % 6271;
> >
> > Just wondering if those constants are arbitrary chosen, or if there is
> > something there to guarantee a good distribution ?
> >
> > If you have some links explaining this algorithm, it would be greatly
> > appreciated!
> > Also, how would you get a good distribution on IPv6. Maybe it would make
> > sense to use murmur ?
>
> This algorithm came from FastMail.fm. Murmur2 may be better, I'm going
> to use it in upcoming upstream hash module which allows to hash any
> expression.
>
>
> --
> Igor Sysoev
>
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