RE: [PATCH] - Fix get_model_name() for mixed cpu type systems

Luck, Tony
2006-10-19T21:22:41Z

> I don't think this is going to work for the simple reason that perfmon supports per-thread
> monitoring. As a thread migrates from one CPU to another, its PMU state migrates with it.
> So you cannot reload a full Montecito state onto a Madison PMU. You will not crash, because
> write to unimplemented PMD are ignored but you will get false results. Even in system-wide
> tools are not prepare to cope with mixed configurations.

Well you could do some ugly things forcing a sched_setaffinity-like call to prevent
the task migrating to an incompatible cpu (but you'd also have to somehow make sure
that the process didn't call sched_setaffinity() itself to undo this).

System wide sounds like an even bigger problem.

Forcing perfmon into "generic" mode sounds like a saner option.

-Tony