I have delayed the release of perfmon2 for 2.6.24 because I have
identified a problem with the current codebase on X86 and
possibly other platforms (except IA-64).
When using timeout-based event set multiplexing, there is a risk
of deadlock. The reason is that there is a race condition between
the PMU interrupt handler and the timer interrupt used by the hrtimers.
I am experimenting with a fix on X86 that consists of changing the
PMU interrupt vector to one which has higher priority than the timer
(set to 0xef). On Itanium, we do not have the problem because
the PMU interrupt vector already has higher priority than the timer.
Please check on your architecture to verify that the PMU
interrupt vector has HIGHER priority that the timer interrupt.