nice-renice-priority general questions!!!!

[Cem Tugrul]

hi Forum,

i have BaaN erp appl and oracle 9.2 Db on my rp2450 production server...all the time when
i run glance i see PRI colon values for users
seems standart and generally 154 and nice value from TOP users have same value 20.
Here are my questions;
Now,Do you think this is normal?
What does the the value of PRI mean?(i mean the difference between PRI 154 and 156 or PRI 254 )
Can i able to change?if so does it affect my sys performance?
How can i set a default nice value for a specific user?(for exa;i want my user name
"picolog" works all the time with a lower PRI
so what must i set NICE for that user?
Best Regards,

from my top out;
CPU TTY PID USERNAME PRI NI SIZE RES STATE TIME %WCPU %CPU COMMAND
1 ? 29790 picolog 241 20 53740K 32196K run 48:11 97.97 97.80 bshell
3 ? 5467 root 152 20 331M 241M run 363:12 90.05 89.89 rds
2 ? 18173 ut4fk 154 20 45548K 24004K sleep 7:01 19.78 19.74 bshell
3 ? 17631 ut2hc 154 20 32236K 10692K sleep 0:59 10.12 10.10 bshell
2 ? 11722 ut2tk 154 20 35308K 13764K sleep 1:47 6.60 6.59 bshell
0 ? 18179 ut4fk 154 20 3681M 9460K sleep 2:48 5.52 5.51 oraclebaan01
5 ? 12755 a8480 154 20 26092K 4548K sleep 0:02 4.95 4.94 bshell


seruser "picolog"
PROCESS LIST Users= 8
User CPU Util Cum Disk Thd
Process Name PID PPID Pri Name ( 800% max) CPU IO Rate RSS Cnt
--------------------------------------------------------------------------------
oraclebaan0 14469 1 237 ut4ca 100/27.6 1875.7 0.0/ 113 24.1mb 1
bshell 29790 29789 241 picolog 100/14.7 624.0 0.0/ 0.5 18.5mb 1
oraclebaan0 28184 1 241 ut0zk 66.6/ 8.1 406.4 0.8/ 4.7 23.0mb 1
bshell 21125 21124 154 ut6sk 52.0/ 5.4 369.2 1.4/ 0.1 23.5mb 1
oraclebaan0 7694 1 237 oracle 44.3/19.9 139.0 0.0/ 0.4 24.2mb 1
bshell 19031 19030 154 picolog 30.5/ 4.4 300.8 0.0/ 0.1 11.5mb 1
bshell 8482 8480 154 ut2ky 30.3/ 0.9 2.2 1.2/ 0.0 5.5mb 1
oraclebaan0 20715 1 154 a8620 21.9/ 0.2 11.5 8.5/ 1.1 25.0mb 1
oraclebaan0 8942 1 154 a1522 12.1/ 2.9 0.7 2.9/ 0.7 24.0mb 1
bshell 29255 29254 154 ut7at 12.1/ 0.3 13.3 0.0/ 0.0 11.5mb 1
oracle8 29256 29255 154 ut7at 9.8/ 0.5 21.3 0.0/ 0.0 12.5mb 1
oracle8 8483 8482 154 ut2ky 8.2/ 0.3 0.7 0.0/ 0.0 3.5mb 1
oraclebaan0 8485 1 154 ut2ky 7.2/ 0.2 0.6 16.2/ 0.4 23.2mb 1
bshell 8939 8938 154 a1522

Best Regards,

[Thierry Poels_1]

hi,

the nice value is controlled by the user or administrator. The default value is 20.
(users can only lower their priority).

The priority is controlled by the system and depends on the nice value, duration, cpu usage, .... You can only influence this by reniceing the process or with rtprio.

regards,
Thierry.

[Cem Tugrul]

Hi Thierry,

i have also read man nice-renice...
fro my user"picolog" i have set nice for his
PID 30...now the nice value=30 of my user "picolog"...
so this means high nice value(>20) processes
run at lower priority and that's i want...

[Thierry Poels_1]

hi,

indeed a higher nice value means a lower priority, and althus a higher PRI value.

But as the priority (PRI) is defined by the system based on several parameters it is possible that processes with higher nice values have temporarily a higher priority than processes with a lower nice value.

regards,
Thierry.

[Sridhar Bhaskarla]

Hi,

If you are not intervening with the system as 'root' to set the priorities, system will decide the priority based on how the process has been behaving over the time.

By default process will be alloted with a nice value of 20. However, depending on their behaviour, their priorities will be adjusted by the system. Processes that started in background or cron will have higher nice values (lower priority). As a user you can only increase (renice) your nice value. To sort the processes by their nice values, run

UNIX95= ps -e -o 'nice pid args' |sort -n

-Sri

[Cem Tugrul]

Thank's...