PRI parameter of ps and top

static priority: 100~139，用來計算dynamic priority與time quantum。可使用nice()/setpriority()改變，nice value -20~19對應到static priority 100~139
dynamic priority: 由sleep time與static priority計算出來，是scheduler實際使用的priority
realtime priority: for realtime process, another story...

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發信人: kenduest.bbs@bbs.cs.nctu.edu.tw (小州), 看板: Linux
標  題: Re: [問題] top/ps 顯示 priority的問題
發信站: 交大資訊次世代ＢＳ２ (Sat Jul 26 16:53:29 2008)
轉信站: ptt!ctu-reader!ctu-peer!news.nctu!csnews.cs.nctu!news.cs.nctu!BS2

※ 引述《mkl0301.bbs@ptt.cc (mkl)》之銘言：
> 再解釋一下我的問題...
> top/ps顯示的nice(NI)值都很正常...
> renice的值  ps的PRI top的PR
> -20              39      0
> 0                19     20
> 19                0     39
> 可是priority的值就怪怪的...
> 尤其是ps..怎麼priority越高,PRI越大呢??
> (priority不是應該值越小priority越高嗎?)

ps -o 是使用 priority, 不是 pri 這個字而已, 輸出的意義用途
不大一樣
|cmd_ni ps_pririty ps_opri ps_pri ps_ni top_pr top_ni
|-20      0           60    39     -20      0    -20
|  0     20           80    19       0     20      0
| 19     39           99     0      19     39     19

root@test-laptop:~# renice -20 -p $pid
9238: old priority 19, new priority -20
root@test-laptop:~# ps -o "pid pri priority opri nice" $pid
PID PRI PRI PRI NI
9238 39 0 60 -20
root@test-laptop:~# renice 0 -p $pid
9238: old priority -20, new priority 0
root@test-laptop:~# ps -o "pid pri priority opri nice" $pid
PID PRI PRI PRI NI
9238 19 20 80 0
root@test-laptop:~# renice 19 -p $pid
9238: old priority 0, new priority 19
root@test-laptop:~# ps -o "pid pri priority opri nice" $pid
PID PRI PRI PRI NI
9238 0 39 99 19
root@test-laptop:~#

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080724
static priority ranging from 100 to 139 (from ULK)

使用renice是會改到process的priority的，只是為什麼ps與top的結果都怪怪的...
真要說的話，至少top的結果是"正常"的，ps的根本反過來了....

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剛剛在試renice，發現renice改的不只是nice值
連priority都會被改到? 而且ps與top的結果不一樣???

cmd_ni ps_pr ps_ni top_pr top_ni
-20    39   -20      0    -20
0    19     0     20      0
19     0    19     39     19

cmd_ni=ps_ni=top_ni
ps_pr=19-cmd_ni
top_pr=20+cmd_ni

root@test-laptop:/# pid=6415;
root@test-laptop:/#
root@test-laptop:/# renice -20 -p $pid;
6415: old priority 19, new priority -20
root@test-laptop:/# ps -o "pid pri ni" $pid;
PID PRI  NI
6415  39 -20
root@test-laptop:/# top -n 1 -p $pid;

top - 01:51:40 up  2:21,  2 users,  load average: 0.40, 0.27, 0.27
Tasks:   1 total,   0 running,   1 sleeping,   0 stopped,   0 zombie
Cpu(s): 13.0%us,  2.3%sy,  0.5%ni, 83.4%id,  0.6%wa,  0.1%hi,  0.0%si,  0.0%st
Mem:   2066408k total,  1423656k used,   642752k free,    52852k buffers
Swap:  2000084k total,        0k used,  2000084k free,   821060k cached

PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                                          
6415 test       0 -20  337m 179m  27m S    4  8.9  24:07.43 firefox                                                                          

root@test-laptop:/# renice 0 -p $pid;
6415: old priority -20, new priority 0
root@test-laptop:/# ps -o "pid pri ni" $pid;
PID PRI  NI
6415  19   0
root@test-laptop:/# top -n 1 -p $pid;

top - 01:51:46 up  2:21,  2 users,  load average: 0.36, 0.26, 0.27
Tasks:   1 total,   0 running,   1 sleeping,   0 stopped,   0 zombie
Cpu(s): 13.0%us,  2.3%sy,  0.5%ni, 83.4%id,  0.6%wa,  0.1%hi,  0.0%si,  0.0%st
Mem:   2066408k total,  1423716k used,   642692k free,    52860k buffers
Swap:  2000084k total,        0k used,  2000084k free,   821060k cached

PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                                          
6415 test      20   0  337m 179m  27m S   10  8.9  24:07.82 firefox                                                                          

root@test-laptop:/# renice 19 -p $pid;
6415: old priority 0, new priority 19
root@test-laptop:/# ps -o "pid pri ni" $pid;
PID PRI  NI
6415   0  19
root@test-laptop:/# top -n 1 -p $pid;

top - 01:51:49 up  2:21,  2 users,  load average: 0.33, 0.26, 0.27
Tasks:   1 total,   0 running,   1 sleeping,   0 stopped,   0 zombie
Cpu(s): 13.0%us,  2.3%sy,  0.5%ni, 83.4%id,  0.6%wa,  0.1%hi,  0.0%si,  0.0%st
Mem:   2066408k total,  1423968k used,   642440k free,    52868k buffers
Swap:  2000084k total,        0k used,  2000084k free,   821052k cached

PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                                          
6415 test      39  19  337m 179m  27m S    4  8.9  24:08.05 firefox                                                                          

root@test-laptop:/#