[Mpi3-tools] lightweight event log
m.a.hermanns at fz-juelich.de
Thu Jul 2 03:58:48 CDT 2009
> 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
Sometimes tools need all parameter information, though. Especially for
higher level analysis, one might need more than the above information.
> 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.
Combining your answers to point 1 and 2, I envision to pre-construct
memory-layouts (like or even with MPI datatypes) to the relevant
information, so that a tool can basically first tell the implementation
what it want to be logged, then define handles for the data layout, and
finally, retrieve the desired information through the defined handles at
the location where they are needed.
I admit I didn't evaluate the implementation overhead for something like
that yet, and I am aware that flexibility usually comes with a runtime cost.
> 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.
I am uncertain whether this logging facility would/should be
complementing or competing with existing tracing tools.
Some MPI implementations already have tracing facilities. To my
knowledge mpich2 has MPE and OpenMPI has vampirtrace. Is this new
logging facility to be provided by these or is it envisioned to be a new
infrastructure. Would this not create competition between measurement
infrastructures within MPI implementations?
Martin mentioned a ring buffer to be queried? What happens when the
buffer is full? If some logging information is lost, what can the user
derive from an incomplete log?
> 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
>> Who are these users? Application developers or tool developers?
>> Best regards,
>> 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
>>> * 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:
>>> If anybody wants to bring up another agenda item, please let me know.
>>> 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
>> Marc-Andre Hermanns
>> Juelich Supercomputing Centre
>> Institute for Advanced Simulation
>> Forschungszentrum Juelich GmbH
>> D-52425 Juelich
>> Phone : +49-2461-61-2054
>> Fax : +49-2461-61-6656
>> eMail : m.a.hermanns at fz-juelich.de
>> WWW : http://www.fz-juelich.de/jsc/
>> JSC is the coordinator of the
>> John von Neumann Institute for Computing
>> and member of the
>> Gauss Centre for Supercomputing
>> Sitz der Gesellschaft: Juelich
>> Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498
>> Vorsitzende des Aufsichtsrats: MinDir'in Baerbel Brumme-Bothe
>> Geschaeftsfuehrung: Prof. Dr. Achim Bachem (Vorsitzender),
>> Dr. Ulrich Krafft (stellv. Vorsitzender),
>> Prof. Dr. Harald Bolt,
>> Prof. Dr. Sebastian M. Schmidt
> 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
> Mpi3-tools mailing list
> Mpi3-tools at lists.mpi-forum.org
Juelich Supercomputing Centre
Institute for Advanced Simulation
Forschungszentrum Juelich GmbH
Phone : +49-2461-61-2054
Fax : +49-2461-61-6656
eMail : m.a.hermanns at fz-juelich.de
WWW : http://www.fz-juelich.de/jsc/
JSC is the coordinator of the
John von Neumann Institute for Computing
and member of the
Gauss Centre for Supercomputing
Sitz der Gesellschaft: Juelich
Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498
Vorsitzende des Aufsichtsrats: MinDir'in Baerbel Brumme-Bothe
Geschaeftsfuehrung: Prof. Dr. Achim Bachem (Vorsitzender),
Dr. Ulrich Krafft (stellv. Vorsitzender),
Prof. Dr. Harald Bolt,
Prof. Dr. Sebastian M. Schmidt
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