RE: [PATCH 00/12] Cqm2: Intel Cache quality monitoring fixes

[Yu, Fenghua]

> From: Andi Kleen [mailto:andi@xxxxxxxxxxxxxx]
> "Luck, Tony" <tony.luck@xxxxxxxxx> writes:
> > 9)	Measure per logical CPU (pick active RMID in same precedence for
> task/cpu as CAT picks CLOSID)
> > 10)	Put multiple CPUs into a group
> 
> I'm not sure this is a real requirement. It's just an optimization, right? If you
> can assign policies to threads, you can implicitly set it per CPU through affinity
> (or the other way around).
> The only benefit would be possibly less context switch overhead, but if all
> the thread (including idle) assigned to a CPU have the same policy it would
> have the same results.
> 
> I suspect dropping this would likely simplify the interface significantly.

Assigning a pid P to a CPU and monitoring the P don't count all events happening on the CPU.
Other processes/threads (e.g. kernel threads) than the assigned P can run on the CPU.
Monitoring P assigned to the CPU is not equal to monitoring the CPU in a lot cases.

Thanks.

-Fenghua