p5-12.c

来自「SUN Solaris8平台下进程间通信」· C语言 代码 · 共 55 行

#include <sys/time.h>
#include <sys/resource.h>
#include <unistd.h>
#include <stdio.h>
#include <math.h>
#include "err_exit.h"
void work()
{
    FILE *fp;
    int i;  double x = 4.5;    
    if ((fp = tmpfile()) == NULL)
       err_exit("tmpfile error");
    for(i = 0; i < 10000; i++){          
        fprintf(fp,"Do some output\n");
        if(ferror(fp)){
            fprintf(stderr,"Error writing to temorary file\n");
            exit(1);
        }
    }
    for(i = 0; i < 1000000; i++)
        x = log(x*x+3.21);
}
int main()
{
    struct rusage r_usage;
    struct rlimit r_limit;
    int priority;
    work();
    /*  查看work用去的CPU时间  */
    getrusage(RUSAGE_SELF,&r_usage);    
    printf("CPU usage: User = %ld.%06ld,System = %ld.%06ld\n",
        r_usage.ru_utime.tv_sec, r_usage.ru_utime.tv_usec,
        r_usage.ru_stime.tv_sec, r_usage.ru_stime.tv_usec);
    /*  获取本进程的微调值  */
    priority=getpriority(PRIO_PROCESS, getpid());
    printf("Current priority=%d\n",priority);
    /*  获取文件大小限制  */
    getrlimit(RLIMIT_FSIZE,&r_limit);
    printf("Current FSIZE limit: soft=%ld, hard=%ld\n",
         r_limit.rlim_cur,r_limit.rlim_max);
    /*  改变文件大小限制为2K  */
    r_limit.rlim_cur = 2048;
    r_limit.rlim_max = 4096;
    printf("Setting a 2K file size limit\n");
    setrlimit(RLIMIT_FSIZE, &r_limit);
    /*  尝试降低微调值  */
    priority=setpriority(PRIO_PROCESS, getpid(),-20);
    if (priority<0&&errno==EACCES)
        printf("non super-user attempted to lower a process priority\n");
    priority=getpriority(PRIO_PROCESS, getpid());
    printf("Current priority=%d\n",priority);
    work();
    return 0;
}