You can use CPU time values in the statistics trace report
to identify specific processes for further investigation when you
analyze the performance of your Db2 subsystem.
The following table shows process that are likely candidates for
further investigation based on the particular CPU time values that
you find in statistics trace report.
Table 1. Major contributors to CPU time in a Db2 subsystem
| |
Applications |
Database services (ssnmDBM1)
address space |
System services (ssnmMSTR)
space |
Internal resources lock manager (IRLM) |
| TCB |
- SQL processing
- Synchronous I/O
- Lock requests
- Logical locking
- Buffer updates
- Group buffer pool reads1
- Global lock requests1
|
- Opening and closing of data sets
- database services address space (ssnmDBM1) full
- System contraction
- Preformat
- Extend
|
- Archiving
- BSDS processing
|
- Error checking
- Management
|
| SRB |
The
same contributors as for TCB, but in preemptable enclave SRB mode
for DDF applications. The values are reported in the accounting TCB
Class 1 and Class 2 CPU instrumentation. |
- Deferred writes
- Prefetch reads
- Parallel child tasks
- Castouts1
- Asynchronous group buffer pool writes1
- P-lock negotiation1
- Notify exit1
- Page set close or pseudo-close to convert to non-GBP dependent1
- Group buffer pool checkpoints1
|
- Physical log writes
- Thread deallocation
- Update commits (including unlocking of page P-locks1)
- Backouts
- Checkpoints
|
- Local IRLM latch contention
- IRLM and XES global contention1
- Asynchronous XES contention1
- P-lock negotiation1
- Deadlock detection
|
notes:
- Applies to data sharing environments only.