On Wed, 16 Oct 2024 17:28:17 +0100
"Medvedkin, Vladimir" <vladimir.medved...@intel.com> wrote:
> Hi Stephen,
>
> On 15/10/2024 23:29, Stephen Hemminger wrote:
> > On Fri, 11 Oct 2024 18:17:00 +0000
> > Vladimir Medvedkin<vladimir.medved...@intel.com> wrote:
> >
> >> +
> >> +uint32_t
> >> +rte_thash_get_rand_poly(uint32_t poly_degree)
> >> +{
> >> + uint32_t ret_poly;
> >> +
> >> + if (poly_degree > 32)
Error log here?
> >> + return 0;
> >> +
> >> + do
> >> + ret_poly = __thash_get_rand_poly(poly_degree);
> >> + while (thash_test_poly_order(ret_poly, poly_degree));
> > Unbounded loop adds some risk, should there be an upper limit on retries.
>
> Thisis the probabilisticpartof the algorithm.
>
> __thash_get_rand_poly() returns a random polynomial that either
> satisfies the order criteria (element <x> of the field must generate
> multiplicative subgroup of order not less than some number), or not. The
> probability that it does not meet this criteria is strictly less than 1.
> Thus, with each attempt, the probability of not finding suitable
> polynomial exponentially tends to zero.
Never trust probabilities to converge. Just add an upper bound of something big
like 32 tries and log error and give up.
>
> >
> >> +
> >> + return ret_poly;
> >> +}
> >> diff --git a/lib/hash/version.map b/lib/hash/version.map
> >> index 4f13f1d5aa..7ce6ab1121 100644
> >> --- a/lib/hash/version.map
> >> +++ b/lib/hash/version.map
> >> @@ -61,4 +61,5 @@ INTERNAL {
> >>
> >> rte_thash_gfni_stub;
> >> rte_thash_gfni_bulk_stub;
> >> + rte_thash_get_rand_poly;
> > Why does this function need to be moved to its own file?
> > Only used in one place in rte_thash.c.
> It was done just for convenience. If you insist, I'll move it to rte_thash.c
It is actually good to put in seperate file, but you can keep the old name.
Best to reserve names with rte_ prefix for user visible prefixes.
