Re: [PATCH] perf_events: fix bug in hw_perf_enable()

[Peter Zijlstra <peterz@infradead.org>]

On Mon, 2010-02-01 at 17:12 +0100, Stephane Eranian wrote:
> > btw, I've also added the below, from what I can make from the docs
> fixed
> > counter 2 is identical to arch perf event 0x013c, as per table A-1
> and
> > A-7. Both are called CPU_CLK_UNHALTED.REF, except for Core2, where
> > 0x013c is called CPU_CLK_UNHALTED.BUS.
> >
> 
> If you measure 0x013c in a generic counter or in fixed counter 2
> it will count the same thing but not at the same rate.
> This is true on Core2, Atom, Nehalem, Westmere. The ratio is the
> clock/bus ratio.

But for Nehalem and Westmere event 0x3c umask 0x01 is referred to as
CPU_CLK_UNHALTED.REF_P (Tables A-2 and A-4), 

Fixed Counter 2 is referred to as CPU_CLK_UNHALTED.REF (Table A-7).

For Core2 and Atom (Table A-8, A-9) it is called CPU_CLK_UNHALTED.BUS,
for these entries there is talk about a fixed ratio.