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
