<分区>
我有以下代码，我在终端中运行。 在另一个终端中，我打开了“top”，在那里我可以看到我创建的新进程的 %CPU。我为进程数 (N) 运行它； 2、4、8、16。 每个我报告的平均 %CPU 是.. 2 - 100% 4 - 97% 8 - 50% 16 - 25%
如何根据这些结果确定计算机的处理能力？
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define N 2 /* define the total number of processes we want */
/* Set global variable */
float total=0;
/* compute function just does something. */
int compute()
{
int i;
float oldtotal=0, result=0;
/* for a large number of times just square root and square
the arbitrary number 1000 */
for(i=0;i<2000000000;i++)
{
result=sqrt(1000.0)*sqrt(1000.0);
}
/* Print the result – should be no surprise */
printf("Result is %f\n",result);
/* We want to keep a running total in the global variable total */
oldtotal = total;
total = oldtotal + result;
/* Print running total so far. */
printf("Total is %f\n",total);
return(0);
}
int main()
{
int pid[N], i, j;
float result=0;
printf("\n"); /* bit of whitespace */
/* We want to loop to create the required number of processes
Note carefully how only the child process is left to run */
for(i=0;i<N;i++)
{
/* Do the fork and catch it if it/one fails */
if((pid[i]=fork())==-1)
{
exit(1);
}
/* now with child we want to do our computation */
else if(pid[i] > 0)
{
/* give a message about the proc ID */
printf("Process Id for process %d is %d\n",i,getpid());
/* call the function to do some computation. If we used sleep
The process would simply sleep. We do not want that */
compute();
/* After we have done our computation we must quit the for
loop otherwise we get a fork bomb! */
break;
}
}
/* nothing else to do so end main function (and program) */
return 0;
}