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一、软件需求

在同时运行多个CPU密集型进程时，需采集以下统计信息：

• 当前运行在逻辑CPU上的进程ID
• 每个进程的运行进度百分比

实验程序设计要求：

1. 命令行参数

参数	说明	示例值
n	并发进程数量	3
total	总运行时长（毫秒）	50
resol	统计间隔（毫秒）	1

2. 进程行为规范

• 每个进程消耗total毫秒CPU时间后结束
• 每resol毫秒记录：
  1. 进程ID（0~n-1）
  2. 累计运行时间（ms）
  3. 进度百分比（(i+1)*100/nrecord，nrecord=total/resol）

二、代码实现

#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <err.h>#define NLOOP_FOR_ESTIMETION 1000000000UL
#define NSEC_PER_SEC    1000000000UL
#define NSEC_PER_MSEC   1000000UL/* 获取纳秒差 */
static inline long diff_nsec(struct timespec before, struct timespec after)
{return ((after.tv_sec * NSEC_PER_SEC + after.tv_nsec) - (before.tv_sec * NSEC_PER_SEC + before.tv_nsec));
}/* 每微秒消耗的空循环的次数 */
static unsigned long loops_per_msec(void)
{struct  timespec before, after;clock_gettime(CLOCK_MONOTONIC, &before);unsigned long i;for(i = 0; i < NLOOP_FOR_ESTIMETION; i++);clock_gettime(CLOCK_MONOTONIC, &after);return ((NLOOP_FOR_ESTIMETION * NSEC_PER_MSEC) / diff_nsec(before, after));
}static inline void load(unsigned long nloops)
{unsigned long i;for(i = 0; i < nloops; i++ );
}static void chidld_fn(int nproc, struct timespec *buf, int nrecord, unsigned long nloop_per_resol, struct timespec start)
{int i;struct timespec ts;for(i = 0; i < nrecord; i++){load(nloop_per_resol);clock_gettime(CLOCK_MONOTONIC, &ts);buf[i] = ts;}printf("nproc\tms\t step\n");printf("---------------------\n");for(i = 0; i < nrecord; i++){printf("%d\t%ld\t%d\n", nproc, diff_nsec(start, buf[i]) / NSEC_PER_MSEC,((i + 1) * 100) / nrecord );}printf("---------------------\n");exit(EXIT_SUCCESS);
}int main(int argc, char *argv[])
{int ret = EXIT_FAILURE;if( 4 > argc){fprintf(stderr, "usage: %s <nproc> <total[ms]> <resolution[ms]>\n", argv[0]);exit(EXIT_FAILURE);}int nproc = atoi(argv[1]); //同时运行的进程的数量int total = atoi(argv[2]); //程序运行的总时长，ms为单位 int resol = atoi(argv[3]); //采集统计信息的间隔if(1 > nproc) //对进程数量参数过滤非法值{fprintf(stderr, "<nproc> (%d) should be >= 1\n", nproc);exit(EXIT_FAILURE);}if(1 > total) //对程序时长参数过滤非法值{fprintf(stderr, "<total> (%d) should be >= 1\n", total);exit(EXIT_FAILURE);}if(1 > resol) //对采集统计信息参数过滤非法值{fprintf(stderr, "<resol> (%d) should be >= 1\n", resol);exit(EXIT_FAILURE);}if(total % resol){fprintf(stderr, "<total> (%d) should be mutliple of <resol> (%d) \n",total, resol);exit(EXIT_FAILURE);}int nrecord = total / resol;struct timespec* logbug = malloc(nrecord * sizeof(struct timespec)); //堆中开辟内存if(!logbug){err(EXIT_FAILURE, "malloc(nrecord) failed");}puts("estimeting workload which just take one millsecond");unsigned long nloops_per_resol = loops_per_msec() * resol;puts("end estimeting");fflush(stdout); // fflush logpid_t* pids = malloc(nrecord * sizeof(pid_t));if(!pids){warn("malloc (pids) failed");goto free_logbuf;}int i, ncreated;struct timespec start;clock_gettime(CLOCK_MONOTONIC, &start);for(i = 0, ncreated = 0; i < nproc; i++, ncreated++){pids[i] = fork();if( 0 > pids[i]){goto wait_children;}else if( 0 == pids[i]){//子进程执行空间chidld_fn(i, logbug, nrecord, nloops_per_resol, start);}}ret = EXIT_SUCCESS;wait_children:if(EXIT_FAILURE == ret) //杀死所有已创建的子进程.{for(i = 0; i < ncreated; i++){if(0 > kill(pids[i], SIGINT)){warn("kill(%d) failed", pids[i]);}}}for(i = 0; i < ncreated; i++) //等待子进程结束{if(0 > wait(NULL)){warn("wait() failed");}}free_pids:free(pids);free_logbuf:free(logbug);exit(ret);
}

三、编译配置（Makefile）

TARGET := app
SRC := sched.c
CPPFLAGS := -pthreadall: $(TARGET)@echo "make successful"$(TARGET): $(SRC)@echo $(SRC)gcc $(CPPFLAGS) $^ -I. -o $@clean:rm $(TARGET)

四、实验结果

nproc   ms      step
---------------------
2       0       2
2       1       4
2       2       6
...
2       172     100
---------------------
nproc   ms      step
---------------------
0       10      2
0       11      4
...
0       176     100
---------------------
nproc   ms      step
---------------------
1       6       2
1       7       4
...
1       203     100