[mpiwg-tools] pvar attribute questions

[Mohror, Kathryn]

Hi Junchao,

I'm trying to understand MPI3 MPI_T performance variables (pvar).  The standard defines pvar sessions, pvar classes (e.g.,COUNTER, HIGHWATERMARK etc), and continuous pvars, readonly pvars.I was wondering if there is any relevance between these concepts. The standard doesn't say that.

For instance, for a highwatermark pvar, I guess it should be continuous. Otherwise, suppose a pvar session starts this pvar, then stops it, and then restarts it.  How can I keep track of this pvar? Let's say during the live period of the pvar, the high watermark is 50. After the pvar is stopped, it went up to as high as 90 (since it may be alive in other pvar sessions). So, when I restart the pvar, what value should I read?

If a variable is not continuous then its value is not updated when it is stopped. So in your example the value would be 50 in the session that stopped the variable and 90 in any sessions that still had the variable live at the time it reached that value. There's a bit more explanation on page 579 starting at line 21. Does that help?

Kathryn


Thanks
--Junchao Zhang

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Kathryn Mohror, kathryn at llnl.gov<mailto:kathryn at llnl.gov>, http://people.llnl.gov/mohror1
CASC @ Lawrence Livermore National Laboratory, Livermore, CA, USA




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