AIX: osysmond.bin High CPU Usage

APPLIES TO:

Oracle Database - Enterprise Edition - Version 11.2.0.3 and later

IBM AIX on POWER Systems (64-bit)

SYMPTOMS

11gR2 or 12cR1 Grid Infrastructure on AIX, observed high CPU usage by osysmond.bin

Name            PID  CPU%  PgSp Owner           PageIn        0  PAGING SPACE

osysmond   11993226  16.7 153.1 root            PageOut       0  Size,MB  

20480

root 14286918        1   7   Jan 06      - 1121:16/grid/product/11.2.0/bin/osysmond.bin       ##>> high accumulated CPU usage     

oracle 17760308 17367264  19   Jan 06      - 388:35 /grid/product/11.2.0/bin/ocssd.bin

root  7602414        1  23   Jan 06      - 381:56 /grid/product/11.2.0/bin/crsd.bin reboot

CAUSE

SOLUTION

Case 1 - high number of disks

The issue happens when there's high number of disks. The disk stat collection is expensive on AIX, this isn't an Oracle issue, it's being jointly worked by IBM and Oracle via bug 13987807

Duplicate bugs: bug 13605859 bug 13614667 bug 13705498 bug 13950866 bug 14221669 bug 14213360

If the high CPU usage has an impact, while IBM is still working to improve disk stat collection API, fix for bug 13987807 should be applied. Refer to note 13987807.8 for details of fixed version. The fix will disable disk stat collection if there's more than 100 disks.

Case 2 - high number of open file descriptor

The issue happens when there's high number of open file descriptor. The traverse of open file descriptor is expensive on AIX, this isn't an Oracle issue, it's being jointly worked by IBM and Oracle via bug 16901346

Duplicate bugs: bug 17056186 bug 18543509 

If the issue has an impact, while IBM is still working to enhance the code, fix for bug 16901346 should be applied. Refer to note 16901346.8 for more information.

REFERENCES

BUG:13605859  - AIX: OSYSMOND.BIN USES MORE CPU THAN OCSSD.BIN CRSD.BIN AND EVMD.BIN COM

BUG:13614667 - 11.2.0.3 OSYSMOND HIGH CPU USAGE

原來這個程序那麼多bug...