Re: [PATCH 2/6 -tip] perf stat: treat same behaviour for all CYCLES and CLOCKS

Paul Mackerras
2009-07-03T08:18:23Z

Ingo Molnar writes:

> Other 'compound' events might be possible too: for example a new
> cache-hits field could be is cache-refs minus cache-misses.

Hmmm, on the MPC7450 family there are events for cache-hits and
cache-misses, so there it would be nice to be able to ask for
cache-refs and have it compute cache-hits plus cache-misses.

> I.e. the simplest model for 'compound' events would be:
>
> X = A / B
> X = A - B
> X = A + B
>
> We could list them in the event table, with a flag that specifies
> which arithmetic operation connects two 'atomic' counters.
>
> Then the adding of a new compound event would only be the matter of
> adding one more line to the event table.

Sounds nice. If we do this we should ensure that the two events
get put into one group if possible.

Paul.