toplev: counter scheduling on ICL+ does not handle nmi watchdog fully

andikleen / pmu-tools

Intel PMU profiling tools

GNU General Public License v2.0

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Closed ak-intel closed 2 years ago

ak-intel commented 2 years ago

The scheduling assumes that the PMU has all 4 lower counters available for events that need to be scheduled on counter 0-3.

But the NMI watchdog could allocate one of those and then the groups wouldn't randomly fail.

toplev knows about the nmi watchdog today, but only reduces the total number of counters.

Handling might need retry handling or probing the PMU with nmi watchdog on?

aayasin commented 2 years ago

Andi, it is better to move NMI watchdog to an upper counter on all products

ak-intel commented 2 years ago

Well I hope the moving to HPET series eventually goes in. Ricardo just posted a new version.