DB2 - Problem description
Problem IT37578 | Status: Closed |
NEW ENVIRONMENT VARIABLE TO TUNE WAIT TIMES BETWEEN UDAPL API CALLS ( LINUX ON IBM Z SYSTEMS ONLY ) | |
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) |