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Problem IT37578
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Status: Closed |
NEW ENVIRONMENT VARIABLE TO TUNE WAIT TIMES BETWEEN UDAPL API CALLS ( LINUX ON IBM Z SYSTEMS ONLY )
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| product: |
DB2 FOR LUW / DB2FORLUW / B50 - DB2 |
| Problem description: |
The default wait times ( For both CF and member ) between
uDAPL API calls to retrieve the complete event is 1 microsecond.
Increasing the wait times might reduce performance but can
decrease the CPU usage on the system ( Member and CF ).
Two new environment variables are added for the CF and member to
adjust the wait times between uDAPL API calls. This allows
users to fine tune the wait times based on their system
requirements and find the most optimal balance between CPU
utilization and performance.
If frequent DMA timeouts error messages are seen inside the
db2diag.log, this indicates that the system is bottlenecked by
the CPU usage and is highly recommended to increase the wait
times to reduce the CPU usage on the system. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* all *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to 11.5 FP7 or later *
**************************************************************** |
| Local Fix: |
How to use the environment variables to tune
To set the Member sleep wait time
Run the command
db2set DB2ENVLIST="CF_CLIENT_UDAPL_POLL_SLEEP_IN_MICROSECONDS"
Modify the db2profile under sqllib_shared and add
export CF_CLIENT_UDAPL_POLL_SLEEP_IN_MICROSECONDS=
If successful then during db2start a similar message to this
would appear inside db2diag.log
2021-06-03-07.13.34.325944-420 I45536A589 LEVEL:
Warning
PID : 25474 TID : 4395618003216 PROC :
db2sysc 2
INSTANCE: tony1 NODE : 002
HOSTNAME: tonywang1-iwu7l-zlinux
EDUID : 13 EDUNAME: db2castructevent 2
FUNCTION: DB2 UDB, RAS/PD component, pdLogCaPrintf, probe:876
DATA #1 :
Changing the value of gClientUdaplPollSleepInMicroseconds to
To set the CF sleep wait time
Run the command
db2set DB2_CF_SERVER_UDAPL_POLL_SLEEP_IN_MICROSECONDS=
Upon setting the reg var, the db2diag.log will show
2021-06-02-12.30.01.459434-420 I129035A358 LEVEL: Event
PID : 26476 TID : 4396870981456 PROC :
db2set
INSTANCE: tony1 NODE : 000
HOSTNAME: tonywang1-iwu7l-zlinux
FUNCTION: DB2 UDB, oper system services, db2set_main, probe:40
CHANGE : CFG DB2SET:
DB2_CF_SERVER_UDAPL_POLL_SLEEP_IN_MICROSECONDS: From: "" To:
"100"
Upon running db2start the cf diag logs will show
2021-06-02-12.32.15.0719158257-480 E123456789A301 LEVEL :
Event
PID : 26840 TID : 2332501936
HOSTNAME : tonywang1-iwu7l-zlinux
FUNCTION : CA svr_init, mgmnt_castart
MESSAGE : Using environment variable value
DATA #1 :
Changing the value of gServerUdaplPollSleepInMicroseconds to |
| Solution |
|
| Workaround |
****************************************************************
* USERS AFFECTED: *
* all *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to 11.5 FP7 or later *
**************************************************************** |
| Comment |
Upgrade to 11.5 FP7 or later |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 12.07.2021
23.11.2021
23.11.2021 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
