What is the difference between metric lts__t_sectors_aperture_sysmem_op_read.sum and lts__d_sectors_fill_sysmem.sum

Hi, i use nsight compute to analysis memory workload, and i am confused about metric lts__t_sectors_aperture_sysmem_op_read.sum and lts__d_sectors_fill_sysmem.sum. What is the difference?

I found some tips about these metric:

  • lts__d_sectors_fill_sysmem.sum: sectors filled from system memory
  • lts__t_sectors_aperture_sysmem_op_read.sum: of LTS sectors accessing system memory (sysmem) for read

If i want to know dram(sysmem) read transactions, which metric is correct? i found from https://docs.nvidia.com/nsight-compute/NsightComputeCli/index.html nsight compute metric lts__t_sectors_aperture_sysmem_op_read.sum is euqal to sysmem_read_transactions , but my test result is not like this.

nvprof sysmem_read_transactions value is 73727
nsight compute metric lts__d_sectors_fill_sysmem.sum is 79264
nsight compute metric lts__t_sectors_aperture_sysmem_op_read.sum is 409745

maybe lts__d_sectors_fill_sysmem.sum is equal to sysmem_read_transactions
Thanks