MPI_Wtime() returns the elapsed time since some arbitrary time in the past.  It is a measure of "wallclock" time, not of CPU time or anything.

On 5/4/2012 3:08 PM, Jingcha Joba wrote:
Lets say I have a code like this
 
start = MPI_Wtime()
<Run the solver>
stop = MPI_Wtime();
 
What happens when right after start=MPI_Wtime(), the timeslice of the process ( from the operating system's perspective not the MPI process) is over, and the operating system schedules a next process, after saving the context switch, and eventually this application would resume, once its process is scheduled back by the os.
 
Does MPI_Wtime() takes care of storing/updating the time when this happens?
 
Of course, part of the answer lies in the implementation of Wtime.

 
On Fri, May 4, 2012 at 3:53 AM, Jeff Squyres <jsquyres@cisco.com> wrote:
On May 3, 2012, at 2:02 PM, Jingcha Joba wrote:

> Not related to this question , but just curious, is Wtime context switch safe ?

Not sure exactly what you're asking here...?

--
Jeff Squyres
jsquyres@cisco.com
For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/


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