PROCEDURE FOR KEEPING ENSURING CPU FREQUENCIES STAY CONSISTENT

This procedure assumes that the BIOS settings allow control of c-states to be levered by the O/S directly.  Here's a set of settings this procedure has been tested with.

Recommended ASU Settings for sandy bridge clusters:

processors_and_memory_asu_settings.txt

 

Two pieces are required:

1)  Changes to  /sys/devices/system/cpu/cpu*/cpufreq/scaling as defined in the set_cpu_perfmode script:

set_cpu_perfmode script



2)  We need to run "set_dma_latency 2"  as part of the post-script procedure to inhibit power-saving c-states.

Source code for set_dma_latency

compile with "cc set_dma_latency.c -o set_dma_latency" and execute from a boot script (set_dma_latency must be kept running to inhibit power saving c-states.