Date: Sun, 18 Jan 2009 15:09:24 +0100 From: Peter Holm <pho@freebsd.org> To: Kostik Belousov <kostikbel@gmail.com> Cc: Dag-Erling Sm?rgrav <des@des.no>, freebsd-arch@freebsd.org Subject: Re: stress2 is now in projects Message-ID: <20090118140924.GA27264@x2.osted.lan> In-Reply-To: <20090118132819.GS48057@deviant.kiev.zoral.com.ua> References: <20090118082145.GA18067@x2.osted.lan> <86iqocstjm.fsf@ds4.des.no> <20090118131028.GA26179@x2.osted.lan> <20090118132819.GS48057@deviant.kiev.zoral.com.ua>
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On Sun, Jan 18, 2009 at 03:28:19PM +0200, Kostik Belousov wrote: > On Sun, Jan 18, 2009 at 02:10:28PM +0100, Peter Holm wrote: > > On Sun, Jan 18, 2009 at 01:11:25PM +0100, Dag-Erling Sm?rgrav wrote: > > > Peter Holm <pho@freebsd.org> 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. > > > > > > > Yes, by design. > > > > > You should at the very least allow the user to specify the random seed. > > > > > > > Yes, it would be interesting to see if this is enough to reproduce a > > problem in a deterministic way. I'll look into this. > > I shall state from my experience using it (or, rather, inspecting bug > reports generated by stress2), that in fact it is quite repeatable. > I.e., when looking into one area, you almost always get _that_ problem, > together with 2-3 related issues. > > Due to the nature of the tests and kernel undeterministic operations, > I think that use of the same random seed gains nothing in regard with > repeatability of the tests. It is an old issue that has come up many times: It would be so great if it was possible to some how record the exact sequence that lead up to a panic and play it back. But on the other hand, as you say, it *is* repeatable. The only issue is that it may take 5 minutes or 5 hours. But I'm still game to see if it is possible at all (in single user mode with no network activity etc.) - Peter
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