T3D Timer Functions

• From Fortran, use irtc()

• From C, use rtclock()

• Resolution = 1 tick = 6.67 nanoseconds
  • This assumes you calibrate to account for overhead

• Man pages exist

• Exactly what these timer function return:
  • CPU time or wallclock?
    • Real time (elapsed wallclock)

  • On timesharing MPP (others using same PEs as you), is the timer running when you're sliced out?
    • T3D not currently timesharing

  • Summing over all PEs or reporting for 1 PE only?
    • One PE only, independent of others

  • If CPU time, is it including or ignoring communication time?
    • Not CPU time; real (wallclock) time always includes comm. time, of course.

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