Re: [perfmon2] [announce] Performance Counters for Linux, v6

[Ingo Molnar <mingo@elte.hu>]

* Luck, Tony <tony.luck@intel.com> wrote:

> > - or the PMU capability is expressed as a special counter type (if it's
> >   useful enough) - and then either the write() method or ioctl is extended
> >   to express attributes we want to set/change while a counter is running.
> 
> The product of:
>         {exotic PMU modes} * {creative performance measurement ideas}
>
> will produce a large number of candidates for these special counters (at 
> least on ia64 ... which has a large number of exotic PMU options).
> 
> I don't think that I'm qualified to judge which of them are "useful 
> enough" to warrant a special counter type.

it should certainly be done on a case by case basis. They need to be 
consciously exposed not just summarily exported to user-space, because PMU 
hw features have security implications so it has to be done all 
explicitly.

	Ingo