Question & Answer
Question
Why does sched_setscheduler() receive OSERR: EPERM?
Answer
It may be found at db2diag.log on a Linux machine with DB2 V10.5 FP8 or others.
It seems that sched_setscheduler() try to change priority of kernel thread but
fails by some reasons.
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2017-04-13-02.47.39.511367 I17354A523 LEVEL: Error (OS)
PID : 26229 TID : 70366391103920 PROC : db2wdog
INSTANCE: db2inst1 NODE : 000
HOSTNAME: db2inst1
EDUID : 2 EDUNAME: db2wdog [db2inst1]
FUNCTION: DB2 UDB, oper system services, sqloSetPriorityHdl, probe:6126
MESSAGE : ZRC=0x83000001=-2097151999
CALLED : OS, -, sched_setscheduler OSERR: EPERM (1)
DATA #1 : String, 51 bytes
Failure setting absolute priority of kernel thread.
2017-04-13-02.47.39.529541 E17878A464 LEVEL: Severe
PID : 26235 TID : 70367141884336 PROC : db2sysc
INSTANCE: db2inst1 NODE : 000
HOSTNAME: db2inst1
EDUID : 14 EDUNAME: db2wlmt
FUNCTION: DB2 UDB, oper system services, sqloRequestSetPriority, probe:7327
MESSAGE : ZRC=0xFFFFFBEE=-1042
SQL1042C An unexpected system error occurred.
DATA #1 : String, 29 bytes
Unable to set thread priority
-----
But this is an known behavior and here is information may share to see the situation.
- There is no db2set parameter to disable the message and no plan to enhance that kind
of feature.
- It is important to know that WLM cannot control thread priorities, in case user hits
performance issues.
- Even if it is root install, and by the output of ps_fel we see that db2wdog is running
as root as expected, may be seen on an unsupported Linux OS.
- It has not been reproduced it on x86 with RHEL7.2 and a root installed instance.
We have seen it only a non-root installed instance has that message.
- Even if it is root install, and by the output of ps_fel we see that db2wdog is
running as root as expected, may be seen when user changes something in their OS
configuration.
- It may be suggested to ignore the messages or try a root install.
Note:
This behavior might be changed without notice in the future. We can confirm whether
this technote is valid or not by reviewing this technote.
Please contact your Sales Rep to submit a potential design change towards a future
release. Or please open a ticket, Request For Enhancement at
https://www.ibm.com/developerworks/rfe/
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Document Information
Modified date:
16 June 2018
UID
swg22004056