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Problem IT38794
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Status: Closed |
DB2 DOES NOT DETECT SMT ON LINUX ON Z SYSTEMS
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| product: |
DB2 FOR LUW / DB2FORLUW / B50 - DB2 |
| Problem description: |
Up to Db2 v11.5.6, Db2 does not detect if simultaneous
multithreading (SMT) is enabled on z processors. Z processors
support SMT since z13.
If Db2 does not know that SMT is in place, Db2 parallelizes the
workload as if each thread can use 1 core on its own. This can
cause CPUs tp get overloaded and at the end the throughput
might suffer on your system.
With this change Db2 detects (via lscpu) the threading degree.
If this new behaviour is detrimental to performance, you can
override the automaticaly detected value by setting the
environment variable OSSE_OVERRIDE_THREADS_PER_CORE to 1 in the
environment of the instance owner, and restart your Db2 instance
so that the new setting takes effect. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* Db2 users on z Linux. *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Db2 v11.5.7.0 *
**************************************************************** |
| Local Fix: |
|
| Solution |
|
| Workaround |
****************************************************************
* USERS AFFECTED: *
* Db2 users on z Linux. *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Db2 v11.5.7.0 *
**************************************************************** |
| Comment |
Fix included in Db2 v11.5.7.0 |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 25.10.2021
30.10.2021
30.10.2021 |
| Problem solved at the following versions (IBM BugInfos) |
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| Problem solved according to the fixlist(s) of the following version(s) |
