On Fri, Dec 11, 2015 at 03:02:01PM +0100, Peter Zijlstra wrote:
> On Fri, Dec 11, 2015 at 03:36:36PM +0200, Alexander Shishkin wrote:
>
> > The pmu driver interface basically adds an extra callback to the
> > pmu driver structure, which validates the filter configuration proposed
> > by the user against what the hardware is actually capable of doing
> > and translates it into something that pmu::start can program into
> > hardware.
>
> > @@ -388,12 +393,38 @@ struct pmu {
> > void (*free_aux) (void *aux); /* optional */
> >
> > /*
> > + * Validate instruction tracing filters: make sure hw supports the
> > + * requested configuration and number of filters.
> > + *
> > + * Configure instruction tracing filters: translate hw-agnostic filter
> > + * into hardware configuration in event::hw::itrace_filters
> > + */
> > + int (*itrace_filter_setup) (struct perf_event *event); /* optional
> > */
> > +
> > + /*
> > * Filter events for PMU-specific reasons.
> > */
> > int (*filter_match) (struct perf_event *event); /* optional
> > */
> > };
>
> Any reason you cannot use pmu::filter_match ?
Maybe I've misunderstood your point, but the two seem quite different.
We introduced pmu::filter_match to apply a SW filter each time we
installed events from a context. We use that on ARM to avoid programming
big events into little cores and vice-versa.
As far as I can see, itrace_filter_setup is closer in operation to
event_init. It can fail at configuration time (long before scheduling
events to cores), and leaves the actual filtering to the HW.
Thanks,
Mark.
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