[mvapich-discuss] wrapping calls to polling functions in MVAPICH2

[Alexander Breslow]

Actually, you may disregard my question.  I have thought of another way to
accomplish what I need to do.

-Alex


On Mon, Aug 12, 2013 at 1:29 PM, Alexander Breslow <abreslow at cs.ucsd.edu>wrote:

> Hi Jeff,
>
> The problem is that I don't want to explicitly time high-level functions
> defined in mpi.h but low-level ones; in particular, I'm not directly
> concerned about the duration of say an MPI_Send or MPI_Recv but what
> percentage of total execution time was spent polling waiting to do useful
> work for each MPI process.  For asynchronous calls such MPI_Isend, I assume
> that this can be relatively easily captured by timing MPI_Wait and all its
> derivatives.  However, I am also interested in timing the waiting that
> occurs in blocking calls such as MPI_Recv.
>
> I realize that this is likely highly implementation dependent, but I am
> okay with that.
>
> -Alex
>
>
> On Mon, Aug 12, 2013 at 12:55 PM, Jeff Hammond <jeff.science at gmail.com>wrote:
>
>> polling and profiling are different things.  your example is for
>> profiling and PMPI is the right way to do that.  you should avoid
>> reinventing the wheel and look at mpiP, TAU, etc. though.
>>
>> if you want to implement asynchrony via polling, then it would help if
>> you gave a clear example of what you want in that respect.
>>
>> jeff
>>
>> On Mon, Aug 12, 2013 at 2:36 PM, Alexander Breslow <abreslow at cs.ucsd.edu>
>> wrote:
>> > Hi,
>> >
>> > I was wondering if there is a single low-level function within MVAPICH2
>> that
>> > implements the polling functionality.  I have seen that polling is
>> > adjustable via the MV2 CM SPIN COUNT environment variable.  My goal is
>> to be
>> > able to time all spinning explicitly.
>> >
>> > If this spinning is implemented by a call to a single function F, I
>> would
>> > like to intercept all calls to that function, and redirect those calls
>> to
>> > another function G that times the duration of each invocation of F.
>> >
>> > G would be something like the following:
>> >
>> > G(args){
>> >
>> > t1 = get_time_ns();
>> > F(args);
>> > t2 = get_time_ns();
>> > register(t2,t1);  // Enqueue for post processing
>> >
>> > }
>> >
>> > This seems feasible via the PMPI interface or by writing a library that
>> uses
>> > DYLD functionality if the spinning/polling function appears in the
>> symbol
>> > table of the respective MVAPICH2 object files.  If this is not possible,
>> > could you please tell me which source files that I would have to modify
>> in
>> > order to achieve what I desire?
>> >
>> > Thanks in advance for your time,
>> > Alex
>> >
>> >
>> > _______________________________________________
>> > mvapich-discuss mailing list
>> > mvapich-discuss at cse.ohio-state.edu
>> > http://mail.cse.ohio-state.edu/mailman/listinfo/mvapich-discuss
>> >
>>
>>
>>
>> --
>> Jeff Hammond
>> jeff.science at gmail.com
>>
>
>
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