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I have a quad core (with hyper threading Technology - HT) I'm running an application which takes 270% CPU (according to TOP command)

  1. What is the total available CPU usage? (is it 400% or 800%?)

    • I'm asking because according to Intel documentation, the HT can up the performance up to 30% cpu, so 800% seem to much, yeah?)

  2. What is the relation between load averages and CPU usage?

Over Killer
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user3668129
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1 Answers1

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1: 800. You have 8 cores visible to the OS - that they are not real cores (due to hyperthreading limitations) is not of concern.

2: Ever bothered reading documentation? Practically there is no relation between load average and CPU uage. Load average is "waiting processes" but that can mean they are waiting for IO, and the CPU may not be busy.

wojciii
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TomTom
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  • Thank's. 1. so I if I want to check if I my app can work at the peak load, I need to check that the top command is showing something that is no more than 800% (and it can be more than 400% but less than 800%) ? 2. To check that my app can work at high load, I need to check the top command and not the Load average ? – user3668129 Jun 08 '14 at 13:53
  • If you manage toget more than 800% you either have a faulty measurement or sell the chip for billions. 800% would be all cores running 100% all the time - more is not possible. – TomTom Jun 08 '14 at 15:10
  • so, I can get more than 400% (for example 600% > 400% * 1.3) ( in spite of Intel documentation of 30% better performance) ? is it right ? – user3668129 Jun 08 '14 at 16:51
  • RTFM what the numbers mean. They are utilizatsion - 30% more power, but still 100% core utilization. – TomTom Jun 08 '14 at 20:31