Hello,

scenario description:

--> AIX 5.2 ML 7 with four POWER 4 processors
--> RAM - 8 Gb
--> Ext. Storage - EMC Symmetrix.
--> Oracle 9.2.0.7 running.
--> Another software running constantly (32 bit software)
--> 32bit compiled kernel because this software requirements.

Copy-paste of a fragment of sar statistics (althouth all day is
similar):
---------------------------------------------------------------------------------------------------------------------
TIME USR SYS WIO IDLE
------------ -------- ------- ------- --------
.......
17:20:01 28 34 5 33
17:25:01 24 33 4 39
17:30:01 21 32 4 43
17:35:01 28 34 4 34
17:40:01 36 35 4 24
17:45:01 23 32 4 41
.......
---------------------------------------------------------------------------------------------------------------------

this is a fragment of vmstat with 1 second interval (look at SY and CS
columns):
---------------------------------------------------------------------------------------------------------------------
r b avm fre re pi po fr sr cy in sy
cs us sy id wa
20 0 1015871 33991 0 0 0 0 0 0 76310 96484 143694 6 32
58 4
38 0 1015995 33863 0 0 0 0 0 0 75893 97185 143800 7 28
61 4
4 0 1015944 33914 0 0 0 0 0 0 71564 91087 126781 27 30
39 4
2 0 1015912 33946 0 0 0 0 0 0 76736 96956 144079 7 31
58 4
42 0 1016145 33634 0 0 0 0 0 0 74030 99762 137739 8 32
55 5
0 1 1015864 33992 0 0 0 0 0 0 75664 97942 138391 11 35
50 5
30 0 1016099 33756 0 0 0 0 0 0 73602 103065 134200 15 34
48 4
10 0 1016165 33690 0 0 0 0 0 0 70432 97337 130521 18 38
40 4
---------------------------------------------------------------------------------------------------------------------

The process that is, in my opinion, causing the problem:
---------------------------------------------------------------------------------------------------------------------
187422 13.2 2.0 157288 155920 - A 05:15:19 432:07

---------------------------------------------------------------------------------------------------------------------

The Context Switch is excesive. I,ve been trying to change AIX
scheduler parameters with schedtune but Ive not any satisfactory
result with SCHED_D, SCHED_R and TIMESLICE.

Ive got same questions:

- This process is multi-threaded, about 150-250 threads a time. How can
I be sure that this process is which is causing this high CS ? We can
change the max threads this process opens but when we use less than
200, the funcinality begins to fail .... so we have 250 max.
- In that case, how can I reduce this excesive use of system cpu ?
- What do you think about ?

Thanks in advance for your attention.