Re: [PATCH v6 07/11] drivers: perf: hisi: Add support for Hisilicon SoC event counters

[Anurup M]

On Friday 31 March 2017 07:53 PM, Mark Rutland wrote:
> On Fri, Mar 31, 2017 at 07:43:20PM +0530, Anurup M wrote:
> > On Thursday 30 March 2017 04:16 PM, Mark Rutland wrote:
> > > > > > > +	/*
> > > > > > > > > > > +	 * We must NOT create groups containing mixed PMUs, although
> > > > > > > > > > > +	 * software events are acceptable
> > > > > > > > > > > +	 */
> > > > > > > > > > > +	if (event->group_leader->pmu != event->pmu &&
> > > > > > > > > > > +	    !is_software_event(event->group_leader))
> > > > > > > > > > > +		return -EINVAL;
> > > > > > > > > > > +
> > > > > > > > > > > +	list_for_each_entry(sibling, &event->group_leader->sibling_list,
> > > > > > > > > > > +			    group_entry)
> > > > > > > > > > > +		if (sibling->pmu != event->pmu && !is_software_event(sibling))
> > > > > > > > > > > +			return -EINVAL;
> > > > > > > Please also check the number of counters.
> > > > > Sorry, I could not follow this comment correctly. Could you please explain ?
> > > > > I check the available counters and update used mask in pmu_add -->
> > > > > get_event_index
> > > What I meant was that here we should ensure that a group does not
> > > contain more events than can fit into counters.
> > >
> > > For example, if the HW had two counters, we should reject any group with
> > > more than two events. Such groups can never be scheduled, and make no
> > > sense.
> > I have referred drivers/bus/arm-cci.c and could find validate_group
> > and validate_event functions,
> > which create a fake_pmu to check the available counters for the
> > events in the group.
> > Is that the same way which is expected here? Please comment.
> Something like that.
>
> I think it's simplest to have a validate_group() function, which counts
> the number of counters used. See my suggestion in [1].

This looks simpler. Thanks for the suggestion.

~Anurup

> Thanks,
> Mark.
>
> [1] 20170331135955.GB6488@leverpostej">https://lkml.kernel.org/r/20170331135955.GB6488@leverpostej