Linux下内存占用和CPU占用的计算

->使用free命令查看内存使用情况：

1.echo 3 > /proc/sys/vm/drop_caches

2.free

或者使用cat /proc/yourpid/status 来查看对应pid的内存占用（VmRSS为当前值，VmHWM为峰值）

（注：linux下的malloc申请100mb内存，并不会马上得到100mb，只会预分配一部分，用到时才另外分配）

->使用top -n 1查看进程的CPU占用情况。

或者使用以下方法计算：

 1         FILE *fp = fopen("/proc/stat", "r");
 2         if (fp) {
 3             char name[64] = { 0 };
 4             char buffer[1024] = { 0 };
 5             static int user0 = 0, total0 = 0;
 6             int user1, nice, sys, idle, iowait, irq, softirq, total1 = 0;
 7 
 8             fgets(buffer, sizeof(buffer), fp);
 9             sscanf(buffer, "%s %d %d %d %d %d %d %d", name, &user1, &nice, &sys,
10                     &idle, &iowait, &irq, &softirq);
11             total1 = user1 + nice + sys + iowait + irq + softirq + idle;
12             if (total1 != total0)
13                 m_iCpuPercent = ((user1 - user0) * 100)/ (double) (total1 - total0);
14             else
15                 m_iCpuPercent = 0;
16             user0 = user1;
17             total0 = total1;
18             fclose(fp);
19         } else {
20             fprintf(stderr, "fopen failed:%s
", strerror(errno));
21         }