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pub
pi
Commits
cf955b1c
Commit
cf955b1c
authored
Jul 11, 2019
by
Neil Gershenfeld
Browse files
wip
parent
bda6e6a2
Pipeline
#3908
passed with stage
in 1 second
Changes
1
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1
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Inline
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MPI/mpipi3.c
0 → 100755
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cf955b1c
/*
* mpipi3.c
* Neil Gershenfeld 7/1/19
* use MPI to evaluate pi by summation,
* including overhead, with multiple iterations
*/
#include <stdio.h>
#include <mpi.h>
#include <sys/time.h>
#include <stdint.h>
//#define NPTS 10000000000
#define NPTS 1000000000
#define NLOOP 10
void
main
(
int
argc
,
char
**
argv
)
{
uint32_t
rank
,
nproc
;
uint64_t
i
,
j
,
istart
,
iend
,
init_time
,
start_time
,
end_time
;
struct
timeval
init
,
start
,
end
;
double
sum
,
pi
,
mflops
,
max
;
gettimeofday
(
&
init
,
NULL
);
MPI_Init
(
&
argc
,
&
argv
);
MPI_Comm_rank
(
MPI_COMM_WORLD
,
&
rank
);
MPI_Comm_size
(
MPI_COMM_WORLD
,
&
nproc
);
max
=
0
;
for
(
j
=
0
;
j
<
NLOOP
;
++
j
)
{
if
(
rank
==
0
)
{
MPI_Barrier
(
MPI_COMM_WORLD
);
gettimeofday
(
&
start
,
NULL
);
istart
=
1
+
rank
*
NPTS
;
iend
=
(
rank
+
1
)
*
NPTS
;
sum
=
0
.
0
;
for
(
i
=
istart
;
i
<=
iend
;
++
i
)
sum
+=
0
.
5
/
((
i
-
0
.
75
)
*
(
i
-
0
.
25
));
MPI_Reduce
(
&
sum
,
&
pi
,
1
,
MPI_DOUBLE
,
MPI_SUM
,
0
,
MPI_COMM_WORLD
);
gettimeofday
(
&
end
,
NULL
);
init_time
=
init
.
tv_sec
*
1e6
+
init
.
tv_usec
;
start_time
=
start
.
tv_sec
*
1e6
+
start
.
tv_usec
;
end_time
=
end
.
tv_sec
*
1e6
+
end
.
tv_usec
;
mflops
=
nproc
*
NPTS
*
(
5
.
0
/
(
end_time
-
start_time
));
printf
(
"processes = %d, NPTS = %ld, pi = %f
\n
"
,
nproc
,
NPTS
,
pi
);
printf
(
"init = %f, time = %f
\n
"
,(
start_time
-
init_time
)
/
1.0e6
,(
end_time
-
start_time
)
/
1.0e6
);
if
(
mflops
>
max
)
max
=
mflops
;
printf
(
"estimated MFlops = %f, max MFlops = %f
\n
"
,
mflops
,
max
);
}
else
{
MPI_Barrier
(
MPI_COMM_WORLD
);
istart
=
1
+
rank
*
NPTS
;
iend
=
(
rank
+
1
)
*
NPTS
;
sum
=
0
.
0
;
for
(
i
=
istart
;
i
<=
iend
;
++
i
)
sum
+=
0
.
5
/
((
i
-
0
.
75
)
*
(
i
-
0
.
25
));
MPI_Reduce
(
&
sum
,
&
pi
,
1
,
MPI_DOUBLE
,
MPI_SUM
,
0
,
MPI_COMM_WORLD
);
}
}
MPI_Finalize
();
}
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