Profiling device memory bandwidth utilization

Hello. I want to inquire about whether it is possible to profile the device memory bandwidth utilization (in percent) with Nsight Compute. If not, is there a way to calculate the value with given metrics such as
lts__t_sectors_aperture_sysmem_op_write.sum.per_second and lts__t_sectors_aperture_sysmem_op_read.sum.per_second?

Yes, you can collect the Memory Workload Analysis sections (header, chart and tables) to get a comprehensive memory analysis, e.g. using

ncu --section "regex:MemoryWorkloadAnalysis(_Chart|_Tables)?" <other args>

These are also part of the ‘full’ section set, so you my want to just use

ncu --set full <other args>

Note that the metrics you referenced are for system memory, not device memory. For the latter, you would want to use dram__bytes_read|write.sum.per_second or dram__bytes_read|write.sum.pct_of_peak_sustained_elapsed. To get the overall max bandwidth, you can use gpu__compute_memory_request_throughput.avg.pct_of_peak_sustained_elapsed. Please refer to the memory workload analysis section file and the respective chart and table (tooltips) in the UI.

1 Like

@felix_dt Thanks for your reply. Just to make an another quick check, can you verify the appropriateness of the metrics that I am using? I am quite uncertain about device L2 metric, since its units are in ‘sectors’. It would be the best if I could extract the device L2 utilization in percentage.

  • smsp__cycles_active.avg.pct_of_peak_sustained_elapsed: SM utilization
  • dram__throughput.avg.pct_of_peak_sustained_elapsed: Device memory utilization
  • dram__bytes_read|write.sum.pct_of_peak_sustained_elapsed: Device memory bandwidth utilization
  • lts__t_sectors.avg.pct_of_peak_sustained_elapsed: Device L2

For SM utilization, I recommend to use sm__throughput.avg.pct_of_peak_sustained_elapsed (see the Speed Of Light section). The others looks correct to me.

Thanks. Your reply was very helpful.

This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.