stress2 is now in projects

Peter Holm peter at
Sun Jan 18 14:29:14 PST 2009

On Sun, Jan 18, 2009 at 12:31:34PM -0800, Alfred Perlstein wrote:
> * Kris Kennaway <kris at> [090118 05:52] wrote:
> > Dag-Erling Sm??rgrav wrote:
> > >Peter Holm <pho at> writes:
> > >>The key functionality of this test suite is that it runs a random
> > >>number of test programs for a random period, in random incarnations
> > >>and in random sequence.
> > >
> > >In other words, it's non-deterministic and non-reproducable.
> > >
> > >You should at the very least allow the user to specify the random seed.
> > >
> > >DES
> > 
> > I doubt this will help at all since the test suite is (by design) 
> > massively parallel, so you're at the mercy of small timing changes.
> If the start and stop times of the scripts were recorded one could
> synch with the original potentially between runs, at least on the
> same hardware it ran.
> Basically, replay the suite based on time instead of random.

During the more than 10 years I have used this test suite with
FreeBSD I have always prioritized the ability to panic the kernel.
I have never looked much into a method of re-creating a test stream.

As I see it, it is a *slight* inconvenience that a panic or deadlock
is not 100% reproducible in time.  A fix for any problem still
needs a thorough test (measured in days), IMHO.

Several methods exists, as I see it, to create a test stream. One
could for example generate the random work list first and then
execute the tests after that.

After a panic you would the have the work list that created the
problem. But would re-running the work list reproduce the panic? I
seriously doubt that.

But there is only one way to find out. It should not be that
hard to create deterministic execution of the the tests.

- Peter

> -Alfred

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