On Mon, Mar 05, 2007 at 08:24:37 -0600, Matthew R. Dempsky wrote:
> On Sun, Mar 04, 2007 at 06:16:57PM +0200, Sami Farin wrote:
> > +static inline void dns_sortip(char *s,unsigned int n)
> > +{
> > + int i;
> > + unsigned int rnd;
> > + char tmp[4];
> > +
> > + n >>= 2;
> > + for (i = n - 1; i > 0; i--) {
> > + rnd = dns_random() % n;
> > + byte_copy(tmp,4,s + (i << 2));
> > + byte_copy(s + (i << 2),4,s + (rnd << 2));
> > + byte_copy(s + (rnd << 2),4,tmp);
> > + }
> > +}
>
> Beware this does not generate the same distribution as:
Not that it matters much, but version 20070305T031624Z
already compares >= 0. It also does one useless loop
if n == 1 before for-loop unless I check for it. But dns_sortip
is called by dnscache only with n == 64 (16).
tdlookup.c:doit() has also dns_random (and divide instruction) usage
which can be optimized... maybe 10-20% (at max) (depending on CPU)
improvement in micro-benchmark of 1000000 queries for which
tinydns returns eight A records.
I can post the patch if someone cares.
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