Re: [PATCH risu] use time() as random seed and introduce --randseed option

[Jun Sun]

Agree on the usefulness of generating the same test.  That is the reason behind adding --randseed option.  Once a seed is set, it always generates the same sequence of instructions.

Basically with this patch,

• by default you will generate random instruction sequences for most testing cases
• you can provide a random seed option in the commandline to generate a deterministic instruction sequence

Without this patch,

• we always get one fixed sequence (ie. random seed == 0 case)
• Otherwise we would have to manually modify code to generate random instruction sequences or generate a different fixed sequence.

Hope this clarifies things a little bit.

Jun

On Wed, May 3, 2023 at 10:05 AM Alex Bennée <alex.bennee@linaro.org> wrote:

Jun Sun <jsun@junsun.net> writes:

> By default, risu currently does not generate random instruction sequences because it uses 0 as the random seed.
> This patch uses time() as random seed and also introduces --randomseed option for deterministic sequence
> generation.

I can see the benefit for being able to change the seed but I think
using time() by default means any given sequence won't be reproducible.
This is useful behaviour if you want to regenerate the same test
sequence on another machine without copying stuff about.

>
> [4. text/x-diff; 0008-add-randseed-option-and-use-time-as-default-seed.patch]...


--
Alex Bennée
Virtualisation Tech Lead @ Linaro