Thanks Dan.
I'm afraid that Simics 3.0 is _not_ deterministic when running multiple processors; apparently this is a new feature in Simics 4.0...
Guess I'll just have to deal with this.
Cheers, /fuad
On Thu, Oct 30, 2008 at 11:10 AM, Dan Gibson <degibson@xxxxxxxx> wrote:
Sorry Fuad, I was thinking of another codebase. What I said before was NOT correct. The following IS correct:
Ruby blindly passes whatever seed it is configured with to srandom(). srandom() is smart enough to treat srandom(0) as srandom(1). There is no call to time(NULL).
Addressing the rest of the non-determinism: * Have you modified Ruby? * Are there any other modules loading? * Check out this thread: https://lists.cs.wisc.edu/archive/gems-users/2008-May/msg00113.shtml
Summary of that thread: /Ruby/ is deterministic. We're not sure if /Simics/ is.
I also don't know how ATMTP might interact.
Regards, Dan
On Wed, Oct 29, 2008 at 4:03 PM, Fuad Tabba <fuad@xxxxxxxxxxxxxxxxx> wrote:
Hi Dan (and everyone else),
Setting the g_RANDOM_SEED to 1 doesn't seem to be working. Two runs of the simulation produce different timing results.
I also searched through the code, srandom is always initialized by g_RANDOM_SEED, and I didn't find an instace where setting g_RANDOM_SEED to 0 would result in passing time(NULL) instead of the seed provided... I've also attached gdb to simics/ruby before loading ruby, with breakpoints set on srandom,srand,random and rand to verify that srandom does indeed get the value I've set for g_RANDOM_SEED, and that it gets called before any calls to random, and my assumptions seem to be correct.
I am using GEMS2.1/ATMTP btw...
Any other ideas or suggestions?
Thanks.
Cheers, /fuad _______________________________________________
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