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I’m working on some measurements and the ping results are intriguing me. I tested it in several scenarios and the results are the same: the ping results are better when the CPU load is higher.

The Round Trip Time decreases from about 30 usec with low CPU to ~5 or less usec with high CPU. In a quadcore machine, a single CPU being used already causes this effect

Anyone has seen this kind of behavior before? It seems to be scheduling of the Linux kernel but I’m not sure.

Thanks! :)

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It takes a few extra microseconds to wake up the CPU. This is the tradeoff with power management, it makes latency a bit worse.

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that's a great theory, do you know how can I test it? –  user193744 Jan 29 '13 at 17:03
    
Turn off power management and watch the difference go away. –  David Schwartz Jan 29 '13 at 17:04
    
thank you (: I'll try to turn it off and I'll get back to you! –  user193744 Jan 29 '13 at 17:10
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