|
Problem IC80305
|
Status: Closed |
PERFORMANCE DEGRADATION CAUSED BY LATCH CONTENTION ON SQLO_LT_SQLP_DBCB__HEADLSNSEM. |
| product: |
DB2 FOR LUW / DB2FORLUW / 970 - DB2 |
| Problem description: |
In high workload circumstance, i.e. many concurrent transaction
commit, there might be many EDUs waiting for latch
SQLO_LT_SQLP_DBCB__headLsnSem in following stacks.
sqloXlatchConflict
sqloXlatchConflict
sqlpUpdateMinBuffLsn
sqlpUpdateLowTran
sqlpScanFirstLsoArrayForLowTran
sqlpEndUowRuntime
sqlpxcm1
sqlrrcom_dps
sqlrrcom
sqlrr_commit
sqljs_ddm_rdbcmm
sqljsParseRdbAccessed
The stack trace might vary. But, due to the heavy latch
contention on headLsnSem, the performance will be impacted
significantly.
The fix for this APAR will reduce the latch contention on
SQLO_LT_SQLP_DBCB__headLsnSem. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* All. *
****************************************************************
* PROBLEM DESCRIPTION: *
* In high workload circumstance, i.e. many concurrent *
* transaction commit, there might be many EDUs waiting for *
* latch SQLO_LT_SQLP_DBCB__headLsnSem in following stacks. *
* *
* sqloXlatchConflict *
* sqloXlatchConflict *
* sqlpUpdateMinBuffLsn *
* sqlpUpdateLowTran *
* sqlpScanFirstLsoArrayForLowTran *
* sqlpEndUowRuntime *
* sqlpxcm1 *
* sqlrrcom_dps *
* sqlrrcom *
* sqlrr_commit *
* sqljs_ddm_rdbcmm *
* sqljsParseRdbAccessed *
* *
* The stack trace might vary. But, due to the heavy latch *
* contention on headLsnSem, the performance will be impacted *
* significantly. *
* *
* The fix for this APAR will reduce the latch contention on *
* SQLO_LT_SQLP_DBCB__headLsnSem. *
* *
* *
* *
* *
* *
* To reduce the chance of hitting this problem, following *
* methods can help increase the frequency of flushing dirty *
* pages. *
* - set db cfg parameter SOFTMAX to a small value less than *
* 100, eg. SOFTMAX=25. *
* - specify separated buffer pool for different temp *
* tablespaces. *
****************************************************************
* RECOMMENDATION: *
* Update to db2 version 9.7 fixpack 6 or later fixpacks. *
**************************************************************** |
| Local Fix: |
To reduce the chance of hitting this problem, following methods
can help increase the frequency of flushing dirty pages.
- set db cfg parameter SOFTMAX to a small value less than 100,
eg. SOFTMAX=25.
- specify separated buffer pool for different temp tablespaces. |
| available fix packs: |
DB2 Version 9.7 Fix Pack 6 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 7 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 8 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 9 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 9a for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 10 for Linux, UNIX, and Windows
|
| Solution |
The enhancement fix is first provided in db2 version 9.7 fixpack
6. |
| Workaround |
To reduce the chance of hitting this problem, following methods
can help increase the frequency of flushing dirty pages.
- set db cfg parameter SOFTMAX to a small value less than 100,
eg. SOFTMAX=25.
- specify separated buffer pool for different temp tablespaces. |
| BUG-Tracking |
forerunner : APAR is sysrouted TO one or more of the following: IC85237
follow-up : |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 08.12.2011
04.06.2012
04.06.2012 |
| Problem solved at the following versions (IBM BugInfos) |
9.7.,
9.7.FP6
|
| Problem solved according to the fixlist(s) of the following version(s) |
| 9.7.0.6
|
 |
