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

Anurup M
2017-03-31T15:05:09Z

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] https://lkml.kernel.org/r/20170331135955.GB6488@leverpostej