觀察priority與CPU使用關係
##terminal 1-1
[root@deyu ~]# cat /dev/zero > /dev/null &
[1] 12977
[root@deyu ~]# cat /dev/zero > /dev/null &
[2] 12978
[root@deyu ~]# cat /dev/zero > /dev/null &
[3] 12979
[root@deyu ~]# cat /dev/zero > /dev/null &
[4] 12980
##terminal 2-1
[root@deyu ~]# top
top - 17:33:03 up 10:51, 9 users, load average: 2.42, 0.68, 0.23
Tasks: 214 total, 5 running, 209 sleeping, 0 stopped, 0 zombie
Cpu(s): 3.2%us, 96.8%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 3021464k total, 1293324k used, 1728140k free, 105432k buffers
Swap: 253936k total, 0k used, 253936k free, 470852k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
12977 root 20 0 98.5m 552 444 R 49.6 0.0 0:42.67 cat
12979 root 20 0 98.5m 552 444 R 49.6 0.0 0:25.05 cat
12978 root 20 0 98.5m 552 444 R 49.4 0.0 0:26.92 cat
12980 root 20 0 98.5m 552 444 R 49.4 0.0 0:24.55 cat
....
##terminal 1-2
[root@deyu ~]# renice -n 10 12977
12977: old priority 0, new priority 10
##terminal 2-2
....
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
12979 root 20 0 98.5m 552 444 R 66.4 0.0 1:47.96 cat
12978 root 20 0 98.5m 552 444 R 64.7 0.0 1:48.84 cat
12980 root 20 0 98.5m 552 444 R 61.4 0.0 1:45.55 cat
12977 root 30 10 98.5m 552 444 R 7.0 0.0 1:34.61 cat
##terminal 1-3
[root@deyu ~]# renice -5 12978
12978: old priority 0, new priority -5
##terminal 2-3
....
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
12978 root 15 -5 98.5m 552 444 R 99.8 0.0 5:59.59 cat
12979 root 20 0 98.5m 552 444 R 47.0 0.0 5:46.56 cat
12980 root 20 0 98.5m 552 444 R 46.9 0.0 5:42.90 cat
12977 root 30 10 98.5m 552 444 R 5.4 0.0 2:00.67 cat
##terminal 1-4
[root@deyu ~]# nice -n 5 cat /dev/zero > /dev/null &
[5] 13130
##terminal 2-4
....
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
12978 root 15 -5 98.5m 552 444 R 99.7 0.0 8:29.42 cat
12980 root 20 0 98.5m 552 444 R 40.2 0.0 6:51.01 cat
12979 root 20 0 98.5m 552 444 R 40.1 0.0 6:54.59 cat
13130 root 25 5 98.5m 552 444 R 13.1 0.0 0:03.88 cat
12977 root 30 10 98.5m 552 444 R 4.2 0.0 2:08.24 cat
r key 12980 4 #renice pid 12980 with nice value 4
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
12978 root 15 -5 98.5m 552 444 R 99.7 0.0 9:44.45 cat
12979 root 20 0 98.5m 552 444 R 41.0 0.0 7:25.43 cat
12980 root 24 4 98.5m 552 444 R 40.9 0.0 7:21.84 cat
13130 root 25 5 98.5m 552 444 R 13.3 0.0 0:13.93 cat
12977 root 30 10 98.5m 552 444 R 4.4 0.0 2:11.54 cat
k key 12978 15 # kill pid 12978 with signal 15
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
12979 root 20 0 98.5m 552 444 R 98.7 0.0 8:13.12 cat
12980 root 24 4 98.5m 552 444 R 47.3 0.0 7:42.19 cat
13130 root 25 5 98.5m 552 444 R 35.7 0.0 0:29.89 cat
12977 root 30 10 98.5m 552 444 R 11.8 0.0 2:16.78 cat
