Adjusting system knobs

Adjusting system knobs

by Thomas Gruber -
Number of replies: 0

Since this years focus is on the adjustment of system knobs for energy efficiency, here is some documentation how to do that:

Fritz:

  • Only setting the CPU frequency is supported: You have to use srun --cpu-freq=X-X:performance with X being the target frequency in kHz. There is no way to deactive Turbo mode.
Testcluster:
  • CPU frequency can be set using likwid-setFrequencies: likwid-setFrequencies -f X
  • De/activate Turbo mode: likwid-setFrequencies -t 0/1
  • Change governor: likwid-setFrequencies -g performance/powersave
  • Remark: Reset the settings to default values with likwid-setFrequencies -reset
  • Uncore frequency: likwid-setFrequencies -umin X -umax X (reset with likwid-setFrequencies -ureset)
  • Prefetchers: likwid-feature -c <hwthread list> -e/-d <prefetcher name>. See --help for usable prefetchers. For reset, enable all prefetchers on all HW threads.
  • Further settings like C-states, powercaps etc. can be set on request.

Please validate the frequency before running benchmarks by measuring the CLOCK group with some application.