C中未定义的struct timeval声明
我有一个代码如下
#include <stdio.h>
#include "mpi.h"
#define NRA 512 /* number of rows in matrix A */
#define NCA 512 /* number of columns in matrix A */
#define NCB 512 /* number of columns in matrix B */
#define MASTER 0 /* taskid of first task */
#define FROM_MASTER 1 /* setting a message type */
#define FROM_WORKER 2 /* setting a message type */
MPI_Status status;
double a[NRA][NCA], /* matrix A to be multiplied */
b[NCA][NCB], /* matrix B to be multiplied */
c[NRA][NCB]; /* result matrix C */
main(int argc, char **argv)
{
int numtasks, /* number of tasks in partition */
taskid, /* a task identifier */
numworkers, /* number of worker tasks */
source, /* task id of message source */
dest, /* task id of message destination */
nbytes, /* number of bytes in message */
mtype, /* message type */
intsize, /* size of an integer in bytes */
dbsize, /* size of a double float in bytes */
rows, /* rows of matrix A sent to each worker */
averow, extra, offset, /* used to determine rows sent to each worker */
i, j, k, /* misc */
count;
struct timeval start, stop;
intsize = sizeof(int);
dbsize = sizeof(double);
MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &taskid);
MPI_Comm_size(MPI_COMM_WORLD, &numtasks);
numworkers = numtasks-1;
//printf(" size of matrix A = %d by %dn",NRA,NCA);
//printf(" size of matrix B = %d by %dn",NRA,NCB);
/*---------------------------- master ----------------------------*/
if (taskid == MASTER) {
printf("Number of worker tasks = %dn",numworkers);
for (i=0; i<NRA; i++)
for (j=0; j<NCA; j++)
a[i][j]= i+j;
for (i=0; i<NCA; i++)
for (j=0; j<NCB; j++)
b[i][j]= i*j;
gettimeofday(&start, 0);
/* send matrix data to the worker tasks */
averow = NRA/numworkers;
extra = NRA%numworkers;
offset = 0;
mtype = FROM_MASTER;
for (dest=1; dest<=numworkers; dest++) {
rows = (dest <= extra) ? averow+1 : averow;
//printf(" Sending %d rows to task %dn",rows,dest);
MPI_Send(&offset, 1, MPI_INT, dest, mtype, MPI_COMM_WORLD);
MPI_Send(&rows, 1, MPI_INT, dest, mtype, MPI_COMM_WORLD);
count = rows*NCA;
MPI_Send(&a[offset][0], count, MPI_DOUBLE, dest, mtype, MPI_COMM_WORLD);
count = NCA*NCB;
MPI_Send(&b, count, MPI_DOUBLE, dest, mtype, MPI_COMM_WORLD);
offset = offset + rows;
}
/* wait for results from all worker tasks */
mtype = FROM_WORKER;
for (i=1; i<=numworkers; i++) {
source = i;
MPI_Recv(&offset, 1, MPI_INT, source, mtype, MPI_COMM_WORLD, &status);
MPI_Recv(&rows, 1, MPI_INT, source, mtype, MPI_COMM_WORLD, &status);
count = rows*NCB;
MPI_Recv(&c[offset][0], count, MPI_DOUBLE, source, mtype, MPI_COMM_WORLD,
&status);
}
#ifdef PRINT
printf("Here is the result matrixn");
for (i=0; i<NRA; i++) {
printf("n");
for (j=0; j<NCB; j++)
printf("%6.2f ", c[i][j]);
}
printf ("n");
#endif
gettimeofday(&stop, 0);
fprintf(stdout,"Time = %.6fnn",
(stop.tv_sec+stop.tv_usec*1e-6)-(start.tv_sec+start.tv_usec*1e-6));
} /* end of master section */
/*---------------------------- worker (slave)----------------------------*/
if (taskid > MASTER) {
mtype = FROM_MASTER;
source = MASTER;
#ifdef PRINT
printf ("Master =%d, mtype=%dn", source, mtype);
#endif
MPI_Recv(&offset, 1, MPI_INT, source, mtype, MPI_COMM_WORLD, &status);
#ifdef PRINT
printf ("offset =%dn", offset);
#endif
MPI_Recv(&rows, 1, MPI_INT, source, mtype, MPI_COMM_WORLD, &status);
#ifdef PRINT
printf ("row =%dn", rows);
#endif
count = rows*NCA;
MPI_Recv(&a, count, MPI_DOUBLE, source, mtype, MPI_COMM_WORLD, &status);
#ifdef PRINT
printf ("a[0][0] =%en", a[0][0]);
#endif
count = NCA*NCB;
MPI_Recv(&b, count, MPI_DOUBLE, source, mtype, MPI_COMM_WORLD, &status);
#ifdef PRINT
printf ("b=n");
#endif
for (k=0; k<NCB; k++)
for (i=0; i<rows; i++) {
c[i][k] = 0.0;
for (j=0; j<NCA; j++)
c[i][k] = c[i][k] + a[i][j] * b[j][k];
}
//mtype = FROM_WORKER;
#ifdef PRINT
printf ("after computern");
#endif
//MPI_Send(&offset, 1, MPI_INT, MASTER, mtype, MPI_COMM_WORLD);
MPI_Send(&offset, 1, MPI_INT, MASTER, FROM_WORKER, MPI_COMM_WORLD);
//MPI_Send(&rows, 1, MPI_INT, MASTER, mtype, MPI_COMM_WORLD);
MPI_Send(&rows, 1, MPI_INT, MASTER, FROM_WORKER, MPI_COMM_WORLD);
//MPI_Send(&c, rows*NCB, MPI_DOUBLE, MASTER, mtype, MPI_COMM_WORLD);
MPI_Send(&c, rows*NCB, MPI_DOUBLE, MASTER, FROM_WORKER, MPI_COMM_WORLD);
#ifdef PRINT
printf ("after sendn");
#endif
} /* end of worker */
MPI_Finalize();
} /* end of main */
当我尝试编译它时，警告是：
matriks.c（43）：错误C2079：'开始'使用未定义的结构'timeval'
matriks.c（43）：错误C2079：'stop'使用未定义的结构'timeval'
matriks.c（65）：警告C4013：'gettimeofday'undefined; 假设extern返回int
matriks.c（111）：错误C2224：'.tv_sec'的左边必须有struct / union类型
matriks.c（111）：错误C2224：'.tv_usec'的左边必须有struct / union类型
matriks.c（111）：错误C2224：'.tv_sec'的左边必须有struct / union类型
matriks.c（111）：错误C2224：'.tv_usec'的左边必须有struct / union类型
请帮忙，我不知道错误在哪里。 谢谢。
我想你可能会发现timeval需要你在POSIX系统下包含sys/time.h （这不是标准的C）。 有关详细信息，请参阅POSIX SUSv2页面。