[英]MPI Total run time
I have one program (which calculates the matrix multiplication with cannon algorithm), is implemented in MPI for C, I have set a clock to see the TOTAL time of this program, with total I mean all the process sum. 我有一个程序(用cannon算法计算矩阵乘法),在MPI中实现C,我设置了一个时钟来查看这个程序的TOTAL时间,总计是指所有的过程总和。
But as a result I get the time of each process. 但结果我得到了每个过程的时间。
Part of my code at the beginning of my main: 我的主要部分开头的部分代码:
clock_t begin, end;
double time_spent;
begin = clock();
/* Initializing */
MPI_Init (&argc, &argv);
Then at the end of my code I have: 然后在我的代码结束时,我有:
MPI_Finalize();
end = clock();
time_spent = (double)(end - begin) / CLOCKS_PER_SEC;
printf("\n\nTIME: %f SECONDS\n\n", time_spent);
Assuming what you want is the sum of the individual times for each of your processes, you will need to: 假设您想要的是每个流程的各个时间的总和,您需要:
MPI_Finalize()
, as you'll need an extra communication; MPI_Finalize()
之前移动您的时间结束度量,因为您需要额外的通信; MPI_Reduce()
to process #0 (for example); MPI_Reduce()
收集各个时间来处理#0(例如); and finally Aside from this, unless you have a compelling reason for doing otherwise, I would encourage you to use MPI_Wtime()
as timer rather than the somewhat misleading clock()
timer. 除此之外,除非你有其他令人信服的理由,否则我鼓励你使用
MPI_Wtime()
作为计时器而不是有些误导性的clock()
计时器。
The code could then look as follow: 然后代码可能如下所示:
int main( int *argc, char* argv[] ) {
MPI_Init( &argc, &argv );
double tbeg = MPI_Wtime();
// a lot of stuff here
// you might want a barrier here...
// MPI_Barrier( MPI_COMM_WORLD );
double elapsedTime = MPI_Wtime() - tbeg;
double totalTime;
MPI_Reduce( &elapsedTime, &totalTime, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD );
if ( rank == 0 ) {
printf( "Total time spent in seconds id %f\n", totalTime );
}
MPI_Finalize();
return 0;
}
Yes of course what you get is correct. 是的,当然你得到的是正确的。
If you want the TOTAL TIME, ie the sum of the time spent in every process, then send the local time_spent
of every node in the master node, perform the summation of the local time_spent
's there and print it. 如果你想要TOTAL TIME,即每个进程花费的时间总和,那么发送主节点中每个节点的本地
time_spent
,在那里执行本地time_spent
的求和并打印它。
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