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Subject: Re: Re: [PATCH 6/7] drivers/perf: hisi_pcie: Merge
 find_related_event() and get_event_idx()
To: Jonathan Cameron <Jonathan.Cameron@Huawei.com>, Yicong Yang
	<yangyicong@huawei.com>
References: <20240204074527.47110-1-yangyicong@huawei.com>
 <20240204074527.47110-7-yangyicong@huawei.com>
 <20240208123946.00006618@Huawei.com>
CC: <will@kernel.org>, <mark.rutland@arm.com>,
	<linux-arm-kernel@lists.infradead.org>, <linux-kernel@vger.kernel.org>,
	<yangyicong@hisilicon.com>, <linuxarm@huawei.com>,
	<prime.zeng@hisilicon.com>, <fanghao11@huawei.com>
From: hejunhao <hejunhao3@huawei.com>
Message-ID: <1c14d50d-fc51-cc34-aa97-358466c19fe6@huawei.com>
Date: Thu, 22 Feb 2024 11:00:44 +0800
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Hi, Jonathan


On 2024/2/8 20:39, Jonathan Cameron wrote:
> On Sun, 4 Feb 2024 15:45:26 +0800
> Yicong Yang <yangyicong@huawei.com> wrote:
>
>> From: Junhao He <hejunhao3@huawei.com>
>>
>> The function xxx_find_related_event() scan all working events to find
>> related events. During this process, we also can find the idle counters.
>> If not found related events, return the first idle counter to simplify
>> the code.
>>
>> Signed-off-by: Junhao He <hejunhao3@huawei.com>
>> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
> A suggestion inline to avoid the magic HISI_PCIE_MAX_COUNTER value
> being used outside of the function.

Thanks for the comments, will fix in next version.

>
>> ---
>>   drivers/perf/hisilicon/hisi_pcie_pmu.c | 55 ++++++++++----------------
>>   1 file changed, 21 insertions(+), 34 deletions(-)
>>
>> diff --git a/drivers/perf/hisilicon/hisi_pcie_pmu.c b/drivers/perf/hisilicon/hisi_pcie_pmu.c
>> index 1b45aeb82859..2edde66675e7 100644
>> --- a/drivers/perf/hisilicon/hisi_pcie_pmu.c
>> +++ b/drivers/perf/hisilicon/hisi_pcie_pmu.c
>> @@ -397,16 +397,24 @@ static u64 hisi_pcie_pmu_read_counter(struct perf_event *event)
>>   	return hisi_pcie_pmu_readq(pcie_pmu, event->hw.event_base, idx);
>>   }
>>   
>> -static int hisi_pcie_pmu_find_related_event(struct hisi_pcie_pmu *pcie_pmu,
>> -					    struct perf_event *event)
>> +/*
>> + * Check all work events, if a relevant event is found then we return it
>> + * first, otherwise return the first idle counter (need to reset).
>> + */
>> +static int hisi_pcie_pmu_get_event_idx(struct hisi_pcie_pmu *pcie_pmu,
>> +					struct perf_event *event)
>>   {
>> +	int first_idle = HISI_PCIE_MAX_COUNTERS;
> 	int first_idle = -EAGAIN;

Yes, I will do that.

>>   	struct perf_event *sibling;
>>   	int idx;
>>   
>>   	for (idx = 0; idx < HISI_PCIE_MAX_COUNTERS; idx++) {
>>   		sibling = pcie_pmu->hw_events[idx];
>> -		if (!sibling)
>> +		if (!sibling) {
>> +			if (first_idle == HISI_PCIE_MAX_COUNTERS)
> if (first_idle == -EAGAIN)

Ok, will fix it.

>
>> +				first_idle = idx;
>>   			continue;
>> +		}
>>   
>>   		/* Related events must be used in group */
>>   		if (hisi_pcie_pmu_cmp_event(sibling, event) &&
>> @@ -414,19 +422,7 @@ static int hisi_pcie_pmu_find_related_event(struct hisi_pcie_pmu *pcie_pmu,
>>   			return idx;
>>   	}
>>   
>> -	return idx;
>> -}
>> -
>> -static int hisi_pcie_pmu_get_event_idx(struct hisi_pcie_pmu *pcie_pmu)
>> -{
>> -	int idx;
>> -
>> -	for (idx = 0; idx < HISI_PCIE_MAX_COUNTERS; idx++) {
>> -		if (!pcie_pmu->hw_events[idx])
>> -			return idx;
>> -	}
>> -
>> -	return -EINVAL;
>> +	return first_idle;
> Then this will return -EAGAIN;

Okay

>>   }
>>   
>>   static void hisi_pcie_pmu_event_update(struct perf_event *event)
>> @@ -552,27 +548,18 @@ static int hisi_pcie_pmu_add(struct perf_event *event, int flags)
>>   
>>   	hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
>>   
>> -	/* Check all working events to find a related event. */
>> -	idx = hisi_pcie_pmu_find_related_event(pcie_pmu, event);
>> -	if (idx < 0)
>> -		return idx;
>> -
>> -	/* Current event shares an enabled counter with the related event */
>> -	if (idx < HISI_PCIE_MAX_COUNTERS) {
>> -		hwc->idx = idx;
>> -		goto start_count;
>> -	}
>> -
>> -	idx = hisi_pcie_pmu_get_event_idx(pcie_pmu);
>> -	if (idx < 0)
>> -		return idx;
>> +	idx = hisi_pcie_pmu_get_event_idx(pcie_pmu, event);
>> +	if (idx == HISI_PCIE_MAX_COUNTERS)
>> +		return -EAGAIN;
> Perhaps simpler to handle first_idle == HISI_PCIE_MAX_COUNTERS as
> an error return in hisi_pcie_pmu_get_event_idx - see above.
>
>   	if (idx < 0)
> 		return idx;

Sure.

>
>>   
>>   	hwc->idx = idx;
>> -	pcie_pmu->hw_events[idx] = event;
>> -	/* Reset Counter to avoid previous statistic interference. */
>> -	hisi_pcie_pmu_reset_counter(pcie_pmu, idx);
>>   
>> -start_count:
>> +	/* No enabled counter found with related event, reset it */
>> +	if (!pcie_pmu->hw_events[idx]) {
>> +		hisi_pcie_pmu_reset_counter(pcie_pmu, idx);
>> +		pcie_pmu->hw_events[idx] = event;
>> +	}
>> +
>>   	if (flags & PERF_EF_START)
>>   		hisi_pcie_pmu_start(event, PERF_EF_RELOAD);
>>   
>