[Beowulf] cpufreq, multiple cores, load

David Mathog mathog at caltech.edu
Wed Mar 10 16:10:09 EST 2010


Guy Coates wrote:
> You can change that schedular behaviour by twiddling
sched_mc_power_savings
> 
> echo 1 > /sys/devices/system/cpu/sched_mc_power_savings
> 
> 
> http://www.lesswatts.org/tips/cpu.php

Good link.  

Setting this option made a slight difference when 2 cpuburn processes
were running, and not for any other number.  Instead of 199W power
consumption was reduced to 171W, and two cores showed 2400 MHz and two
1000 MHz, instead of all 4 at 2400 MHz.  Hopefully AMD has addressed
this in later processors, because the 40W hit induced by rev'ing up all
cores on a processor is much bigger than the ~16W hit associated with
actually running the program.

Thanks,

David Mathog
mathog at caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech
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