Re: [discuss] Re: 2.6.19-rc5: known regressions (v3)

[Andi Kleen]

On Wednesday 15 November 2006 19:39, Andrew Morton wrote:
> On Wed, 15 Nov 2006 17:48:05 +0100
> Andi Kleen <ak@xxxxxxx> wrote:
> 
> > 
> > > OProfile has a simplistic view of the performance monitoring hardware. The 
> > > routines in libop/op_alloc_counter.c determine what set of performance registers 
> > > is available from the processor in use. There is no check to see what registers 
> > > are actually available in the /dev/oprofile directory.
> > > 
> > > opcontrol executes ophelp to determine which specific counters to count which 
> > > events. The function map_event_to_counter() in libop/op_alloc_counter.c does the 
> > > actual selection. It seems what is needed is for map_event_to_counter() to check 
> > > to see which counters are available and mark the others as unavailable
> > 
> > Thanks for the explanation. Can you please fix it and release a new version? 
> > Documentation/Changes could be adapted then.
> > 
> 
> Meanwhile we should restore the NMI counter to fix this bug.

No, it was always oprofile who was buggy here, silently taking 
the nmi watchdog away.

-Andi
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