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

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Date:   Fri, 31 Mar 2017 19:43:20 +0530
From:   Anurup M <anurupvasu@...il.com>
To:     Mark Rutland <mark.rutland@....com>
Cc:     will.deacon@....com, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, anurup.m@...wei.com,
        zhangshaokun@...ilicon.com, tanxiaojun@...wei.com,
        xuwei5@...ilicon.com, sanil.kumar@...ilicon.com,
        john.garry@...wei.com, gabriele.paoloni@...wei.com,
        shiju.jose@...wei.com, huangdaode@...ilicon.com,
        linuxarm@...wei.com, dikshit.n@...wei.com, shyju.pv@...wei.com
Subject: Re: [PATCH v6 07/11] drivers: perf: hisi: Add support for Hisilicon
 SoC event counters



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.

Thanks,
Anurup

> Thanks,
> Mark.