Re: [BUG] perf stat: explicit grouping yields unexpected results

[Vince Weaver]

On Fri, 15 Nov 2013, Ingo Molnar wrote:
> 
> Btw., does the kernel side currently support discovery of such 
> impossible group scheduling constraints at group setup time? If not 
> then it probably should and it should reject them straight away.

It does not, or at least I'm pretty sure it can't if the NMI watchdog is 
enabled (Stephane, are you doing your tests with NMI watchdog disabled?)

This is a big problem with PAPI.  If the NMI watchdog is enabled you can't 
tell if a group will fail until the first read, the kernel can't tell you 
at setup time.

Vince
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