[mpiwg-tools] pvar attribute questions

[Mohror, Kathryn]

This looks like Junchao's mail from a while back was released by a moderator. I believe we already satisfied him on this point.

Junchao, please let me know if I am incorrect.

Kathryn

On Aug 30, 2013, at 3:13 PM, Junchao Zhang <junchao.zhang at gmail.com<mailto:junchao.zhang at gmail.com>> wrote:

If the pvar is restarted by the first session, what will be read into this pvar?
I think it is 90. But this value of high watermark did not happen in the live period of the pvar in the first session. So the value 90 doesn't make sense.

I don't know how to let a watermark pvar show different values in different sessions. For COUNTER, TIMER, AGGREGATE pvars, I know we can compute delta between current value and start value. But for watermark pvars, the approach does not apply.



On Fri, Aug 30, 2013 at 4:48 PM, Mohror, Kathryn <mohror1 at llnl.gov<mailto:mohror1 at llnl.gov>> wrote:
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
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--
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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