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Scali MPI Connect Release 4.4 Users Guide 42

1: MPI_Comm_rank 1 3.1us 3.1us 1 3.1us 3.1us

1: MPI_Comm_size 1 1.5us 1.5us 1 1.5us 1.5us

1: MPI_Gather 1 109.9us 109.9us 1 109.9us 109.9us

1: MPI_Init 1 1.0s 1.0s 1 1.0s 1.0s

1: MPI_Keyval_free 1 1.2us 1.2us 1 1.2us 1.2us

1: MPI_Reduce 1 51.5us 51.5us 1 51.5us 51.5us

1: MPI_Scatter 1 138.7us 138.7us 1 138.7us 138.7us

1: Sum 9 1.0s 112.8ms 9 1.0s 112.8ms

1: Overhead 0 0.0ns 9 27.2us 3.0us

1: =====================================================================

0: 13.26.40 -------------Delta---------- ---------Total----------

0: Init+0.111598 s #calls time tim/cal #calls time tim/cal

0: MPI_Bcast 2 79.6us 39.8us 2 79.6us 39.8us

0: MPI_Comm_rank 1 3.3us 3.3us 1 3.3us 3.3us

0: MPI_Comm_size 1 1.4us 1.4us 1 1.4us 1.4us

0: MPI_Gather 1 648.8us 648.8us 1 648.8us 648.8us

0: MPI_Init 1 965.9ms 965.9ms 1 965.9ms 965.9ms

0: MPI_Keyval_free 1 1.1us 1.1us 1 1.1us 1.1us

0: MPI_Reduce 1 37.6ms 37.6ms 1 37.6ms 37.6ms

0: MPI_Scatter 1 258.1us 258.1us 1 258.1us 258.1us

0: Sum 9 1.0s 111.6ms 9 1.0s 111.6ms

0: Overhead 0 0.0ns 9 35.6us 4.0us

0: =====================================================================

The <seconds> field can be set to a large number in order to collect only final statistics.

We see that the output gives statistics about which MPI calls are used and their frequency and

timing. Both delta numbers since last printout and the total accumulated statistics. By setting

the interval timing (in -s <seconds>) to a large number, only the cumulative statistics at the

end are printed. The timings are presented for each process, and with many processes this can

yield a huge amount of output. There are many options for modifying SCAMPI_TIMING to

reduce this output. The selection parameter can time only those MPI processes to be

monitored. There are also other ways to minimize the output, by screening away selected MPI

calls either before or after a certain number of calls or between an interval of calls. Some

examples are:

The rest of the format has the following fields:

where

<MPIcall> is the name of the MPI-call

<Dcalls> is the number of calls to <MPIcall> since the last printout

<Dtime> is the sum of the execution-time for calls to <MPIcall> since the

last printout

<Dfreq> is the average time-per-call for calls to <MPIcall> since the last

printout

<Tcalls> is the number of calls to <MPIcall>

<Ttime> is the sum of the execution-time for calls to <MPIcall>

<Tfreq> is the average time-per-call for calls to <MPIcall>

After all detail-lines (one per MPI-call which has been called since last printout), there will be

a line with the sum of all calls followed by a line giving the overhead introduced when obtaining

the timing measurements.

The second part containing the buffer-statistics has two types of lines, one for receives and one

for sends.

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