[RTEMS Project] #3456: Add support for CPU counter timestamps

[RTEMS trac]

#3456: Add support for CPU counter timestamps
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  Reporter:  Sebastian Huber  |      Owner:  Sebastian Huber
      Type:  enhancement      |     Status:  assigned
  Priority:  normal           |  Milestone:  5.1
 Component:  score            |    Version:  5
  Severity:  normal           |   Keywords:
Blocked By:                   |   Blocking:
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 The original use case for the CPU counter was low level profiling of SMP
 synchronization primitives and busy wait loops for device drivers.

 For low overhead timestamps the CPU counter may be also used, e.g. for
 tracing. To support timestamps, the CPU counter must increment
 monotonically within the whole range of the CPU counter data type, e.g.
 32-bit unsigned integer. In addition, it should not be affected by power
 saving states of the processor.

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Ticket URL: <http://devel.rtems.org/ticket/3456>
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