On Wed, Jan 16, 2013 at 01:13:18PM +0000, Will Deacon wrote:
> On Tue, Jan 15, 2013 at 01:39:50PM +0000, Jiri Olsa wrote:
> > hi,
>
> Hi Jiri,
>
> > adding support to predefine event ratios formulas so they could
> > be used easily in perf.
> >
> > The formulas are handed in the config file with following format:
> >
> > set {
> > events = {cycles,instructions,branch-instructions}:u
> >
> > cpi {
> > formula = cycles / instructions
> > desc = cycles per instruction
> > }
> >
> > branch-rate {
> > formula = branch-instructions / instructions
> > desc = branch rate
> > }
> > }
> >
> > The 'set' defines set of counter that share same events.
> > Each 'set' defines:
> > events - event string that would go into stat/record -e option
> > counters - any number of counters based on above events
> >
> > Each counter (cpi/branch-rate) defines
> > formula - formula with that produce the counter number
> > event names and numbers could be used
> > desc - text description of the counter
> >
> > The formula can currently contain any event from the set::events
> > plus any number (int). There'll be support in future for outside
> > values runtime and other if needed.
>
> Just to say that I *really* like this idea! If we extended it to include
> other operators then it would help us on ARM, where we often have events
> like 'cache accesses' and 'cache misses' but not 'cache hits'.
great, thanks for sharing this
The current operators set is just basic one to show the idea,
it can/will be expanded.
>
> > My current thinking is to have generic formulas file(s) for architectural
> > events and add arch-specific ones once when we have the support for
> > non-architectural events (already sent RFC, v2 is on its way..).
>
> Would the architectural formula files also be in userspace, or is there any
> merit to including useful PMU-specific formulae in sysfs, along with the
> other PMU files?
hum, isn't this too specific for sysfs files?
I think that's going to be the perf tool specific info.. so it's going
to be placed in its configuration files.
jirka
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