Comparing NeXus and FIO I/O

Here is a comparison of NeXus and FIO I/O based on the test cases of table 4.6 (5.2.2020).

Scan command: 
  %dscan exp_dmy01 -0.1 0.1 100 0.1

Elapsed times for different measurement groups:  

                               fio          nxs        nxs + fio
  d1_c01                       18.7s (46%)  19.4 (48%) 19.7 (49%) 
  d1_c01 - d1_c04              20.2s (50%)  21.0 (52%) 21.7 (54%)
  d1_c01 - d1_c12              23.5s (57%)  24.6 (59%) 25.8 (61%)
  d1_c01, mca-2048             38.3s (74%)  21.1 (52%) 22.8 (58%)
  d1_c01, mca-4096             47.9s (79%)  21.6 (53%) 23.2 (56%)
  d1_c01, mca-8192             67.9s (85%)  21.8 (54%) 25.1 (60%) 
  d1_c01, i-petra:             19.6s (49%)  20.5 (51%) 21.3 (53%)
  d1_c01 - d1_c12, mca-2048    42.2s (76%)  27.0 (63%) 28.9 (65%)

The tests displayed in the above table have been carried out to compare FIO and NeXus I/O. We see that the overhead due to NeXus is less than 10%, even if NeXus and FIO are written in parallel. We conclude that the performance reduction generated by NeXus is acceptable.



2020-08-05