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[Bug 1193073] Re: cpu usage does not match sum of per-process usage


Closing Invalid (actually a Won't Fix though - see above comment)

** Changed in: linux (Ubuntu)
       Status: In Progress => Invalid

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  cpu usage does not match sum of per-process usage

Status in “linux” package in Ubuntu:

Bug description:
  Ubuntu 12.04.  Already tested with kernel 3.10 as well.

  1 Get on a system with 2 cpus, netperf and top installed (need m1.medium)
  2. Stop already running netserver
  3. sudo taskset -c 0 netserver
  4. taskset -c 1 netperf -H localhost -l 3600 -t TCP_RR & (start netperf with priority on cpu1)
  5. Run top, press 1 for multiple CPUs to be separated
  6. Observe how the numbers don't add up (varies between being off by 3-7% or so) between the process's numbers and the CPU%

  The numbers also do not add up correctly when viewed directly from /proc
  Bonus. Run htop to see a completely different set of seemingly wrong results.

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