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I'm installing ATLAS on a multicore system. It runs Rocks OS, a linux distro specialized for cluster computing. I need to turn CPU throttling off.

According to a guide at csrc.tamu-commerce.edu, "$ /usr/bin/cpufreq-selector -g performance" turns off throttling on one CPU, but not all of them. They provide a way to turn off others, but does this control each CPU, or each individual core?

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Note: I may have posted this in the wrong place, wasn't entirely sure. –  zarose Apr 3 '11 at 20:43
    
Do you have more than one CPU? It should work for all cores and all cpus... Unless you have a Xeon or Opteron or something you probably only have a single physical CPU. –  tjameson Apr 3 '11 at 21:28
    
I asked my professor who said, "I can't remember how many CPUs there are. It's at least a 2 quad cores in each machine." I looked in /sys/devices/system/cpu/ which has a directory for cpu0 through cpu15, so I'm assuming each core is considered a CPU. Would that be farfetched? –  zarose Apr 3 '11 at 21:47
    
Yeah, each core is considered to be a separate processor, and often if hyperthreading is enabled, then you'll get twice the processors (hyper-threading turns one physical core into two virtual cores). You're probably using a Nehelem or Westmere Xeon processor. –  tjameson Apr 3 '11 at 21:55
    
Check in /proc/cpuinfo as well, but there probably are 16 processors listed there as well. –  tjameson Apr 3 '11 at 21:56

1 Answer 1

You could loop through the cores and set the governor for each.

CORES=$(cat /sys/devices/system/cpu/possible | tr '-' ' ')
for CPU in $(seq $CORES); do
    /usr/bin/cpufreq-selector -g performance -c $CPU
done

A good place for this code would be /etc/rc.local.

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I haven't tried this for two reasons. First, I found out that someone else has already turned throttling off for all the CPUs. Second, I have limited time. I do want to see if this will work later on though. –  zarose Apr 4 '11 at 2:32

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