December 2013
Intermediate to advanced
496 pages
8h 57m
Chinese
Content preview from LINUX系統程式設計 第二版
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時間
|
399
EFAULT
ts
是一個無效的指標。
EINVAL
clock_id
在此系統上是一個無效的時間來源。
下面的範例程式碼可以從四種標準的時間來源取得當前時間：
clockid_t clocks[] = {
CLOCK_REALTIME,
CLOCK_MONOTONIC,
CLOCK_PROCESS_CPUTIME_ID,
CLOCK_THREAD_CPUTIME_ID,
CLOCK_MONOTONIC_RAW,
(clockid_t)
−
1 };
int i;
for (i = 0; clocks[i] != (clockid_t)
−
1; i++) {
struct timespec ts;
int ret;
ret = clock_gettime (clocks[i], &ts);
if (ret)
perror ("clock_gettime");
else
printf ("clock=%d sec=%ld nsec=%ld\n",
clocks[i], ts.tv_sec, ts.tv_nsec);
}
取得行程時間
times()
系統呼叫可用於取得正在運行之行程與它的子行程的行程時間，以時鐘週期
（clock tick）計：
#include <sys/times.h>
struct tms {
clock_t tms_utime; /* user time consumed */
clock_t tms_stime; /* system time consumed */
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.