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/. > As Alex mentioned, the ETM drivers were initially developed when the AUX > buffer was not available. The sysfs interface is there only for the backward compatibility and for bring up ( due to the nature of the > connections between the CoreSight components and sometimes the missing engineering spec). > got it. thanks for the explanation. Regards, Yicong > Suzuki > > .
