Re: perf_counters: page fault trace record

[Paul Mackerras]

Corey Ashford writes:

> Paul Mackerras wrote:
> > Can't you do what you need just using a page fault software counter
> > with sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_ADDR and
> > sample_period = 1?
> 
> I thought about that, but I was under the (incorrect?) impression that 
> on Power, the PERF_SAMPLE_ADDR would be set by the value of the SDAR 
> register, which wouldn't be correct for the case of a page fault.

No, the PERF_SAMPLE_ADDR value only comes from SDAR for a hardware
counter overflow event.  For the page-fault software counter the
PERF_SAMPLE_ADDR value will always be the faulting address.

Paul.
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