Re: [PATCH v2] eal: allow setting random number generator seed

[Stephen Hemminger <stephen@networkplumber.org>]

On Mon, 14 Sep 2026 13:29:22 +0200
Mattias Rönnblom <hofors@lysator.liu.se> wrote:

> Den 2026-09-12 kl. 18:16, skrev Stephen Hemminger:
> > Many performance tests use rte_rand() and the random number
> > can perturb the results. Add an ability to override the automatic
> > random seed on DPDK startup.  
> 
> There is a way to seed the PRNG already, rte_srand(). Why the tests 
> can't use this?
> 
> Provided the test results depend on something that use the PRNG before 
> the test driver has had the opportunity to call rte_srand(), controlling 
> the *initial* seed may be required.
> 
> I don't think this feature should be controlled by an environment 
> variable. There is no precedent for that. If this functionality is 
> deemed useful, it should be an EAL command line option, it seems to me.

There are several tests already using rte_srand() so that is one option.
The choice of environment variable was to match the existing test harness
infrastructure that uses MALLOC_PERTURB to pre-seed malloc.