Timers

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	Note: Feel free to make corrections -- MM		Note: Feel free to make corrections -- MM
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Revision as of 13:33, 21 October 2010

This page serves as a gateway for information related to computing the elapsed time between two positions in your software.

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