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System Time

 
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THX 1138



Joined: 30 Jun 2011
Posts: 103

PostPosted: Mon Jul 09, 2012 12:47 pm    Post subject: System Time Reply with quote

When I ran a program on the Pgroup profilerthe largest amout of time was system time. In my case on the basis of time it made uo 67% of the time. What does this mean and how can I reduce it? It seems that it wiould be impossible to reduce system time.

Thanks in advance.

THX 1138
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mkcolg



Joined: 30 Jun 2004
Posts: 6211
Location: The Portland Group Inc.

PostPosted: Mon Jul 09, 2012 2:17 pm    Post subject: Reply with quote

Hi THX 1138,

System time is the time spent executing code other than what is part of your host program. So calls to your OS libraries like malloc, sleep, open, etc., would be put here. Also, if you are running GPU programs, the time spent running of the device and copying data would be put there as well.

What you need to do is determine where the system time is coming from using a profiler. Only then can you tell if/how to reduce it.

- Mat
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THX 1138



Joined: 30 Jun 2011
Posts: 103

PostPosted: Tue Jul 10, 2012 7:18 am    Post subject: Reply with quote

Okay, how do I do that? How I do I tell if thw system time is coming from the from using the profiler?

Also, sometimes the system times does not show up in the output. Sometimes, only the functions of my program show up in the output.. So what did I do to get the system time put in, or what did I do to get rid it it in the output?

Thanks in advance.

THx 1138
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mkcolg



Joined: 30 Jun 2004
Posts: 6211
Location: The Portland Group Inc.

PostPosted: Wed Jul 11, 2012 8:06 am    Post subject: Reply with quote

Hi THX 1138,

For information on using the PGI Profiler, please see[url] http://www.pgroup.com/doc/pgprofug.pdf[/url].

Quote:
How I do I tell if thw system time is coming from the from using the profiler?
Note that I want you to profile the code to see where the system time is coming from, not that the system time is coming from using the profiler.
Quote:

Also, sometimes the system times does not show up in the output. Sometimes, only the functions of my program show up in the output.. So what did I do to get the system time put in, or what did I do to get rid it it in the output?
Instead of using the "-Mprof" flags to instrument your code, use the "pgcollect" utility. While pgcollect is sample based so not as accurate, it does profile the entire program including system routines. "-Mprof" only instruments user code.

- Mat
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THX 1138



Joined: 30 Jun 2011
Posts: 103

PostPosted: Wed Jul 11, 2012 11:48 am    Post subject: PGcollect Reply with quote

I was using pgcollect. I know there are other ways to profile, but I used

pgcollect ./prog

and the results is what I said before.

Thanks in advance.

Newport_j
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