[Linux] What is monotonic time

 

今天在使用strike tune performanc 發現裡面會使用，查了一下所有的clock monotonic 就是指monotonic time 就是指單調的時間，

就是指系統開機後的時間，例如範例裡指的1302313，會算過後就大概是15天，大概跟系統的uptime 差不多，

CLOCK_REALTIME指的就是wall time，通常是有變量jiffies 鯠記錄。這時間通常是指epoch time 就是從1970-01-01起經歷的秒數，

主要是由變數xtime控制

 

#strace  -p [PID]

stat("/etc/localtime", {st_mode=S_IFREG|0644, st_size=118, ...}) = 0
recvfrom(3, 0x71c8774, 7, 0, 0, 0) = -1 EAGAIN (Resource temporarily unavailable)
clock_gettime(CLOCK_MONOTONIC, {1302313, 979356034}) = 0
clock_gettime(CLOCK_MONOTONIC, {1302313, 979398583}) = 0
epoll_wait(19, {{EPOLLIN, {u32=3, u64=352187318275}}}, 64, 947) = 1
clock_gettime(CLOCK_MONOTONIC, {1302313, 987120032}) = 0
recvfrom(3, "\1\0\2\0\0\0-", 7, 0, NULL, NULL) = 7
recvfrom(3, "\0<\0<\5None2\0\0\0\0\0\6\352}\0\10celeryev\20wor"..., 45, 0, NULL, NULL) = 45
recvfrom(3, "\316", 1, 0, NULL, NULL) = 1
recvfrom(3, "\2\0\2\0\0\0d", 7, 0, NULL, NULL) = 7
recvfrom(3, "\0<\0\0\0\0\0\0\0\0\1^\370\0\20application/json\5"..., 100, 0, NULL, NULL) = 100
recvfrom(