[Mpi3-tools] lightweight event log

William Gropp wgropp at illinois.edu
Wed Jul 1 13:08:55 CDT 2009

Hi Marc-Andre,

The idea is that the implementation may be instrumented with the  
ability to record timestamped events.  Like the "variable" interface,  
the idea here is to provide a way to expose whatever the  
implementation is prepared to make available, such as information that  
the developers and tuners of that implementation have found valuable.   
So in answer to your questoins:

1) what will be logged? Probably timestamps, some indication of  
location, and some context (like message length).  I would not expect  
all routine parameters to be logged, though an implementation could  
choose to do thiat

2) it is lightweight for two reasons: (1) the data logged may be as  
small and simple as the implementation chooses and (2) the data may be  
logged in an internal, time and space efficient format.  A separate  
set of routines are provided to interpret the logged data.  For  
example, the timestamps may be stored in an internal format (such as  
the bits from a clock register) and converted to seconds only when the  
user evaluates the logged data.

3) A performance tool can examine the log files but (as part of the  
light-weight part) there is no option to invoke a method or routine at  
every point a log record could be created.

"Users" here means users with some degree of sophistication.   
Basically, if you can use PAPI and really understand what the various  
counters mean, then you should be able to use this interface.


On Jun 29, 2009, at 7:42 AM, Marc-Andre Hermanns wrote:

> Hi Martin,
> I am interested in how this logging facility is meant. Do you have a
> more detailed description of it somewhere?
> - What do you anticipate to be logged (despite of timestamps)?
> - What will make it lightweight?
> - Is there any way that a performance tool might hook into?
> "[...] Users can then read and evaluate this event log at a later  
> time.
> [...]"
> Who are these users? Application developers or tool developers?
> Best regards,
> Marc-Andre
> Martin Schulz wrote:
>> Hi all,
>> As discussed during the last meeting, our next MPI 3 tools WG TelCon
>> is on 6/29
>> at the usual time (8am PDT, 11am EDT, 5pm MSZ). The dial-in numbers
>> are as
>> usual:
>>     * Toll Free Dial In Number for Offsite Participants: 866-914-3976
>>     * International Access/Caller Paid Dial In Number: 925-424-8105
>>     * Dial In Number for LLNL Onsite Participants: 4-8105
>>     * Access Security Code: 860609 #
>> So far, the agenda is to talk about a proposal for a general
>> performance information
>> interface. More information on this proposal is at:
>> https://svn.mpi-forum.org/trac/mpi-forum-web/wiki/MPI3Tools/pimpi
>> If anybody wants to bring up another agenda item, please let me know.
>> Martin
>> _______________________________________________________________________
>> Martin Schulz, schulzm at llnl.gov, http:// people.llnl.gov/schulz6
>> CASC @ Lawrence Livermore National Laboratory, Livermore, USA
>> _______________________________________________
>> Mpi3-tools mailing list
>> Mpi3-tools at lists.mpi-forum.org
>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-tools
> -- 
> Marc-Andre Hermanns
> Juelich Supercomputing Centre
> Institute for Advanced Simulation
> Forschungszentrum Juelich GmbH
> D-52425 Juelich
> Germany
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William Gropp
Deputy Director for Research
Institute for Advanced Computing Applications and Technologies
Paul and Cynthia Saylor Professor of Computer Science
University of Illinois Urbana-Champaign

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