linux-kernel - Re: [RESEND PATCH V7 2/2] drivers/perf: hisi: add driver for HNS3 PMU

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Message-ID: <639b6a40-139e-60c4-6792-b65b965ab844@huawei.com>
Date:   Mon, 27 Jun 2022 22:31:54 +0800
From:   "huangguangbin (A)" <huangguangbin2@...wei.com>
To:     Will Deacon <will@...nel.org>
CC:     <john.garry@...wei.com>, <mark.rutland@....com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linuxarm@...wei.com>,
        <liuqi115@...wei.com>, <zhangshaokun@...ilicon.com>,
        <f.fangjian@...wei.com>, <lipeng321@...wei.com>,
        <shenjian15@...wei.com>
Subject: Re: [RESEND PATCH V7 2/2] drivers/perf: hisi: add driver for HNS3 PMU



On 2022/6/27 18:52, Will Deacon wrote:
> On Wed, May 25, 2022 at 08:52:11AM +0800, Guangbin Huang wrote:
>> HNS3(HiSilicon Network System 3) PMU is RCiEP device in HiSilicon SoC NIC,
>> supports collection of performance statistics such as bandwidth, latency,
>> packet rate and interrupt rate.
>>
>> NIC of each SICL has one PMU device for it. Driver registers each PMU
>> device to perf, and exports information of supported events, filter mode of
>> each event, bdf range, hardware clock frequency, identifier and so on via
>> sysfs.
>>
>> Each PMU device has its own registers of control, counters and interrupt,
>> and it supports 8 hardware events, each hardward event has its own
>> registers for configuration, counters and interrupt.
>>
>> Filter options contains:
>> event        - select event
>> port         - select physical port of nic
>> tc           - select tc(must be used with port)
>> func         - select PF/VF
>> queue        - select queue of PF/VF(must be used with func)
>> intr         - select interrupt number(must be used with func)
>> global       - select all functions of IO DIE
>>
>> Signed-off-by: Guangbin Huang <huangguangbin2@...wei.com>
>> Reviewed-by: John Garry <john.garry@...wei.com>
>> Reviewed-by: Shaokun Zhang <zhangshaokun@...ilicon.com>
>> ---
>>   MAINTAINERS                       |    6 +
>>   drivers/perf/hisilicon/Kconfig    |   10 +
>>   drivers/perf/hisilicon/Makefile   |    1 +
>>   drivers/perf/hisilicon/hns3_pmu.c | 1662 +++++++++++++++++++++++++++++
>>   include/linux/cpuhotplug.h        |    1 +
>>   5 files changed, 1680 insertions(+)
>>   create mode 100644 drivers/perf/hisilicon/hns3_pmu.c
> 
> This mostly looks good to me, but I have one niggling concern with the ABI:
> 
>> +#define HNS3_PMU_FILTER_ATTR(_name, _config, _start, _end)               \
>> +	static inline u64 hns3_pmu_get_##_name(struct perf_event *event) \
>> +	{                                                                \
>> +		return FIELD_GET(GENMASK_ULL(_end, _start),              \
>> +				 event->attr._config);                   \
>> +	}
>> +
>> +HNS3_PMU_FILTER_ATTR(event, config, 0, 16);
>> +HNS3_PMU_FILTER_ATTR(subevent, config, 0, 7);
>> +HNS3_PMU_FILTER_ATTR(event_type, config, 8, 15);
>> +HNS3_PMU_FILTER_ATTR(ext_counter_used, config, 16, 16);
>> +HNS3_PMU_FILTER_ATTR(real_event, config, 0, 15);
> 
> How does perf tool deal with overlapping fields like this? It seems like
> quite a bad idea to allow things like "event=0xffff,subevent=0" when they
> are no longer distinct and I don't _think_ any other drivers do this.
> 
> Can you remove 'event' and 'real_event' for now, or are they needed?
> 
> Will
> .
> 
Ok, I will modify this part.