From: Suzuki K Poulose <suzuki.poulose@arm.com>
To: Yicong Yang <yangyicong@hisilicon.com>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, coresight@lists.linaro.org,
linux-pci@vger.kernel.org
Cc: alexander.shishkin@linux.intel.com, helgaas@kernel.org,
gregkh@linuxfoundation.org, lorenzo.pieralisi@arm.com,
will@kernel.org, mark.rutland@arm.com,
mathieu.poirier@linaro.org, mike.leach@linaro.org,
leo.yan@linaro.org, jonathan.cameron@huawei.com,
song.bao.hua@hisilicon.com, john.garry@huawei.com,
prime.zeng@huawei.com, liuqi115@huawei.com,
zhangshaokun@hisilicon.com, linuxarm@huawei.com
Subject: Re: [PATCH RESEND 0/4] Add support for HiSilicon PCIe Tune and Trace device
Date: Mon, 19 Apr 2021 17:11:46 +0100 [thread overview]
Message-ID: <e98fdb87-1834-c5eb-70be-4e739ff258bd@arm.com> (raw)
In-Reply-To: <fb4e70d9-e5c8-1cbf-ca21-adb701089fe0@hisilicon.com>
On 19/04/2021 14:21, Yicong Yang wrote:
> On 2021/4/19 19:17, Suzuki K Poulose wrote:
>> On 17/04/2021 11:17, Yicong Yang wrote:
>>> [RESEND with perf and coresight folks Cc'ed]
>>>
>>> HiSilicon PCIe tune and trace device (PTT) is a PCIe Root Complex
>>> integrated Endpoint (RCiEP) device, providing the capability
>>> to dynamically monitor and tune the PCIe traffic (tune),
>>> and trace the TLP headers (trace).
>>>
>>> PTT tune is designed for monitoring and adjusting PCIe link parameters.
>>> We provide several parameters of the PCIe link. Through the driver,
>>> user can adjust the value of certain parameter to affect the PCIe link
>>> for the purpose of enhancing the performance in certian situation.
>>
>> ...
>>
>>>
>>> The reason for not using perf is because there is no current support
>>> for uncore tracing in the perf facilities. We have our own format
>>> of data and don't need perf doing the parsing. The setting through
>>> perf tools doesn't seem to be friendly as well. For example,
>>> we cannot count on perf to decode the usual format BDF number like
>>> <domain>:<bus>:<dev>.<fn>, which user can use to filter the TLP
>>> headers through the PTT device.
>>>
>>> A similar approach for implementing this function is ETM, which use
>>> sysfs for configuring and a character device for dumping data.
>>>
>>> Greg has some comments on our implementation and doesn't advocate
>>> to build driver on debugfs [1]. So I resend this series to
>>> collect more feedbacks on the implementation of this driver.
>>>
>>> Hi perf and ETM related experts, is it suggested to adapt this driver
>>> to perf? Or is the debugfs approach acceptable? Otherwise use
>>> sysfs + character device like ETM and use perf tools for decoding it?
>>> Any comments is welcomed.
>>
>> Please use perf. Debugfs / sysfs is not the right place for these things.
>>
>
> ok.
>
>> Also, please move your driver to drivers/perf/
>>
>
> Does it make sense as it's a tuning and tracing device, and doesn't have counters
> nor do the sampling like usual PMU device under drivers/perf/.
It doesn't matter. As long as you can drive it via the perf interface,
it can live there. The CoreSight was added way before there was kind
of a suitable place like the above. You could find other uncore PMUs
under drivers/perf.
Suzuki
prev parent reply other threads:[~2021-04-19 16:11 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-17 10:17 [PATCH RESEND 0/4] Add support for HiSilicon PCIe Tune and Trace device Yicong Yang
2021-04-17 10:17 ` [PATCH RESEND 1/4] hwtracing: Add trace function " Yicong Yang
2021-04-17 10:17 ` [PATCH RESEND 2/4] hwtracing: Add tune " Yicong Yang
2021-04-17 10:17 ` [PATCH RESEND 3/4] docs: Add HiSilicon PTT device driver documentation Yicong Yang
2021-04-19 9:07 ` Daniel Thompson
2021-04-19 13:12 ` Yicong Yang
2021-04-17 10:17 ` [PATCH RESEND 4/4] MAINTAINERS: Add maintainer for HiSilicon PTT driver Yicong Yang
2021-04-17 13:56 ` [PATCH RESEND 0/4] Add support for HiSilicon PCIe Tune and Trace device Alexander Shishkin
2021-04-19 13:03 ` Yicong Yang
2021-04-22 3:49 ` Leo Yan
2021-04-22 12:54 ` Yicong Yang
2021-04-19 11:17 ` Suzuki K Poulose
2021-04-19 13:21 ` Yicong Yang
2021-04-19 16:11 ` Suzuki K Poulose [this message]
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