About tsc clock rate

[DoubleRedX]

In the file: include/hip/std/detail/__config line119， What is tsc clock rate？How can i query the tsc clock rate on my GPU？thanks!

[psamfass]

Thank you for reaching out and for your interest in using libhipcxx.

The time stamp counter (TSC) clock rate defines the frequency of the realtime clock on the GPU in which the counter is incremented. This rate can be used to convert clock ticks into actual time and varies depending on the device.

For example, with the MI200, you can refer to the ISA document available at the following link for information regarding the clock rate: MI200 CDNA2 ISA. Within this document, section 8.2.5 states:

8.2.5. S_MEMREALTIME
This instruction reads a 64-bit "real time-counter" and returns the value into a pair of SGPRS:
SDST and SDST+1. The time value is from a constant 25MHz clock (not affected by power
modes or core clock frequency changes)

Additionally, you can conveniently query the clock rate using HIP APIs. For more details, please refer to the documentation here: HIP Timer Functions. Below is an example code snippet for querying the clock rate:

int wallClkRate = 0; //in kilohertz
hipDeviceGetAttribute(&wallClkRate, hipDeviceAttributeWallClockRate, deviceId);

If you have any further questions, please feel free to ask.

[DoubleRedX]

THANK YOU! THANK YOU SO MUCH!