Re: Performance counter API review was [patch] Performance Counters for Linux, v3

Peter Zijlstra
2009-02-04T10:52:34Z

On Wed, 2009-02-04 at 21:47 +1100, Paul Mackerras wrote:
> Peter Zijlstra writes:
>
> > How is smp_call_function() going to help here? You still need to pull
> > all that data through that one FD. That's a cacheline bounce fest.
>
> Well, let's put this into perspective. We would be collecting 8 bytes
> of data from each CPU. Hardly a "cacheline bounce fest". :)

Ah, I was thinking more of the event triggered profiling, like NMI time,
cachemiss or pagefault profiling.

In those cases you'd get a continuous stream of data for each cpu, at
possibly quite high speeds.