[shivam543]

I changed data_volume to 8GB and ran on my 4 year old laptop (Amd Ryzen 4800H + 2 x 8GB 3200MHz DDR4 running NixOS with Linux 6.1.71) I get around 36 GB/s

  1 20.9 
  2 33.4 
  3 35.7 
  4 36.2 
  5 35.2 
  6 35.4 
  7 34.7 
  8 34.9 
  9 34.0 
  10 34.2 
  11 34.4 
  12 34.3 
  13 33.8 
  14 33.6 
  15 33.4 
  16 32.9
 

I expected 51.2 GB/s (2 x 3200 x 1e6 Transfers/s of 8 bytes each)

[adrian_b]

Either because it is a laptop CPU or (less likely) because it is an older Zen 2 might prevent it to reach the DRAM throughput.

Running the test on a desktop Zen 3 (5900X) with slower ECC DDR4-2666, i.e. with a maximum throughput of 42.7 GB/s, provides for 2 or more threads a throughput around 39 GB/s, with a maximum of 39.5 GB/s at 4 threads.