Timers

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==C/C++== ==C/C++==
-1- cycle counting (rdtsc cycle counter)+1- cycle counting (rdtsc cycle counter) - [http://www.mcs.anl.gov/~kazutomo/rdtsc.html source code]
* precise (CS) * precise (CS)
* cpu frequency required * cpu frequency required

Revision as of 13:32, 21 October 2010

C/C++

1- cycle counting (rdtsc cycle counter) - source code

  • precise (CS)
  • cpu frequency required
  • low cost and resolution (OS)

2- MPI_WTime()

  • May offer a high resolution than 1 second.(CS)

3- MPI_WTick()

  • can be queried to determine resolution. (CS)

4- getTimeOfDay() and friends (sys/time.h)

  • portable (BM)
  • not always precise or accurate (BM)
  • may be relatively expensive on IBM BG (compared to cycle counting) (OS)

5- time.h/ctime.h functions (Reference : http://www.cppreference.com/wiki/c/date/start )

  • Have a higher resolution than 1 second (CS)
  • clock function returns elapsed CPU cycles (CS)
  • Needs cpu frequency which may be inaccurate on POSIX compilers (CS)

Note: Feel free to make corrections -- MM

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