Messages in this thread | | | Subject | Re: [PATCH RESEND 0/4] Add support for HiSilicon PCIe Tune and Trace device | From | Suzuki K Poulose <> | Date | Mon, 19 Apr 2021 17:11:46 +0100 |
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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
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