GPU metrics in the Nsight System


I am profiling a CUDA application in Nsight System and wondering what is “GPC Clock Frequency” and “SYS Clock Frequency” in GPU metrics. I am getting different values from those clocks, and I can’t find the information of what it is anywhere, including the Nsight System documentation.

Please see User Guide — nsight-systems 2023.4.1 documentation (link to “Available metrics”).

  • GPC Clock Frequency - gpc__cycles_elapsed.avg.per_second
    The average GPC clock frequency in hertz. In public documentation the GPC clock may be called the “Application” clock, “Graphic” clock, “Base” clock, or “Boost” clock. Note: The collection mechanism for GPC can result in a small fluctuation between samples.

  • SYS Clock Frequency - sys__cycles_elapsed.avg.per_second
    The average SYS clock frequency in hertz. The GPU front end (command processor), copy engines, and the performance monitor run at the SYS clock. On Turing and NVIDIA GA100 GPUs the sampling frequency is based upon a period of SYS clocks (not time) so samples per second will vary with SYS clock. On NVIDIA GA10x GPUs the sampling frequency is based upon a fixed frequency clock. The maximum frequency scales linearly with the SYS clock.