Times - Class 3 - Suspensions
This topic shows detailed information about "Accounting - Times - Class 3 - Suspensions".
This block shows information for Class 3 Suspensions.
The following example shows both layouts, the report on the left, and the trace layout on the right.
Accounting - Times - Class 3 - Suspensions
The field labels shown in the following sample layout of "Accounting - Times - Class 3 - Suspensions" are described in the following section.
Report:
CLASS 3 SUSPENSIONS AVERAGE TIME AV.EVENT TIME/EVENT
-------------------- ------------ -------- ----------
LOCK/LATCH(DB2+IRLM) 0.000000 0.00 N/C
IRLM LOCK+LATCH 0.000000 0.00 N/C
DB2 LATCH 0.000000 0.00 N/C
SYNCHRON. I/O 0.000254 0.83 0.000305
DATABASE I/O 0.000254 0.83 0.000305
LOG WRITE I/O 0.000000 0.00 N/C
OTHER READ I/O 0.000446 0.33 0.001338
OTHER WRTE I/O 0.000000 0.00 N/C
SER.TASK SWTCH 0.000000 0.00 N/C
UPDATE COMMIT 0.000000 0.00 N/C
OPEN/CLOSE 0.000000 0.00 N/C
SYSLGRNG REC 0.000000 0.00 N/C
EXT/DEL/DEF 0.000000 0.00 N/C
OTHER SERVICE 0.000000 0.00 N/C
ARC.LOG(QUIES) 0.000000 0.00 N/C
LOG READ 0.000000 0.00 N/C
DRAIN LOCK 0.000000 0.00 N/C
CLAIM RELEASE 0.000000 0.00 N/C
PAGE LATCH 0.000000 0.00 N/C
NOTIFY MSGS 0.000000 0.00 N/C
GLOBAL CONTENTION 0.000000 0.00 N/C
COMMIT PH1 WRITE I/O 0.000000 0.00 N/C
ASYNCH CF REQUESTS 0.000000 0.00 N/C
TCP/IP LOB XML 0.000000 0.00 N/C
ACCELERATOR 0.000000 0.00 N/C
AUTONOMOUS PROCEDURE N/A N/A N/A
PQ SYNCHRONIZATION N/A N/A N/A
LOB COMPRESSION 0.000000 0.00 N/C
FAST INSERT PIPE 0.000000 0.00 N/C
TOTAL CLASS 3 0.000700 1.17 0.000600
Trace:
CLASS 3 SUSPENSIONS ELAPSED TIME EVENTS TIME/EVENT
-------------------- ------------ -------- ----------
LOCK/LATCH(DB2+IRLM) 0.000000 0 N/C
IRLM LOCK+LATCH 0.000000 0 N/C
DB2 LATCH 0.000000 0 N/C
SYNCHRON. I/O 0.001523 5 0.000305
DATABASE I/O 0.001523 5 0.000305
LOG WRITE I/O 0.000000 0 N/C
OTHER READ I/O 0.002676 2 0.001338
OTHER WRTE I/O 0.000000 0 N/C
SER.TASK SWTCH 0.000000 0 N/C
UPDATE COMMIT 0.000000 0 N/C
OPEN/CLOSE 0.000000 0 N/C
SYSLGRNG REC 0.000000 0 N/C
EXT/DEL/DEF 0.000000 0 N/C
OTHER SERVICE 0.000000 0 N/C
ARC.LOG(QUIES) 0.000000 0 N/C
LOG READ 0.000000 0 N/C
DRAIN LOCK 0.000000 0 N/C
CLAIM RELEASE 0.000000 0 N/C
PAGE LATCH 0.000000 0 N/C
NOTIFY MSGS 0.000000 0 N/C
GLOBAL CONTENTION 0.000000 0 N/C
COMMIT PH1 WRITE I/O 0.000000 0 N/C
ASYNCH CF REQUESTS 0.000000 0 N/C
TCP/IP LOB XML 0.000000 0 N/C
ACCELERATOR 0.000000 0 N/C
AUTONOMOUS PROCEDURE N/A N/A N/A
PQ SYNCHRONIZATION N/A N/A N/A
LOB COMPRESSION 0.000000 0 N/C
FAST INSERT PIPE 0.000111 1 N/C
TOTAL CLASS 3 0.004199 7 0.000600 - LOCK/LATCH(DB2+IRLM) - AVERAGE TIME/ELAPSED TIME
The sum of the accumulated wait time due to local contention for locks and the accumulated wait time due to latch contention.
Field Name: AWTLOLA
- LOCK/LATCH(DB2+IRLM) - AV.EVENT/EVENTS
The sum of the number of wait trace events processed for waits for local contention for locks and the number of wait trace events processed for waits for latch contention.
Note: The internally defined field adjusts the original DB2® value. DB2 counts each event twice, one for the entry and one for the exit.Field Name: ADLLSUSC
This is an exception field.
- IRLM LOCK+LATCH - AVERAGE TIME/ELAPSED TIME
The accumulated wait time because of local contention for locks. The term local contention is used to differentiate from global contention (which is reported in QWACAWTJ). Local contention does not require intersystem communication. The contention is detected and resolved entirely within this subsystem.
Field Name: QWACAWTL
This is an exception field.
- IRLM LOCK+LATCH - AV.EVENT/EVENTS
The number of wait trace events processed for waits for local contention for locks.
Note: The internally defined field adjusts the original DB2 value. DB2 counts each event twice, one for the entry and one for the exit.Field Name: ADLBSUSC
- DB2 LATCH - AVERAGE TIME/ELAPSED TIME
The accumulated wait time because of latch contention.
Field Name: QWACAWLH
- DB2 LATCH - AV.EVENT/EVENTS
The number of wait trace events processed for waits for latch contention.
Note: The internally defined field adjusts the original DB2 value. DB2 counts each event twice, one for the entry and one for the exit.Field Name: ADLASUSC
- SYNCHRON. I/O - AVERAGE TIME/ELAPSED TIME
The I/O elapsed time accumulated due to synchronous I/O suspensions. DB2 calculates this value by subtracting the store clock time when an agent begins waiting for a synchronous I/O from the time the agent is resumed.
Field Name: ADIOSUST
- SYNCHRON. I/O - AV.EVENT/EVENTS
The total number of synchronous I/O suspensions.
Field Name: ADIOSUSC
- DATABASE I/O - AVERAGE TIME/ELAPSED TIME
The accumulated I/O elapsed wait time for database I/O done under this thread. This field is for synchronous I/O only. It includes synchronous read and write I/O. This value is an average.
Field Name: QWACAWTI
- DATABASE I/O - AV.EVENT/EVENTS
The number of wait trace events processed for waits for database I/O under this thread.
Field Name: ADIOARNE
- LOG WRITE I/O - AVERAGE TIME/ELAPSED TIME
The accumulated wait time for log write I/O.
This value is an average.
Field Name: QWACAWLG
- LOG WRITE I/O - AV.EVENT/EVENTS
The number of wait trace events processed for waits for log write I/O. This value is an average.
Field Name: ADLWSUSC
- OTHER READ I/O - AVERAGE TIME/ELAPSED TIME
- The accumulated waiting time due to a read I/O that performed under a thread other than the one being reported. The time does not represent the total duration of the subject read I/O. It includes:
- Sequential prefetch
- List prefetch
Dynamic Prefetch
- Synchronous read I/O performed by a thread other than the one being reported
Field Name: QWACAWTR
This is an exception field.
- OTHER READ I/O - AV.EVENT/EVENTS
The total number of suspensions due to a read I/O performed under a thread other than the one being reported.
Field Name: ADARSUSC
This is an exception field.
- OTHER WRTE I/O - AVERAGE TIME/ELAPSED TIME
- The accumulated waiting time due to a write I/O that performed under a thread other than the one being reported. This time does not represent the total duration of the subject write I/O. It includes:
- An asynchronous write I/O
- A synchronous write I/O performed by a thread other than the one being reported
- Frequent system checkpoints and low settings for deferred
write thresholds
- When updating a page that is being written,
the first thread wait is captured under Other Write I/O
- Other concurrent threads on the same DB2 subsystem
will encounter Page latch suspension.
Field Name: QWACAWTW
This is an exception field.
- OTHER WRTE I/O - AV.EVENT/EVENTS
- The total number of suspensions due to a write I/O performed under a thread other than the one being reported. It includes:
- An asynchronous write I/O
- A synchronous write I/O performed by a thread other than the one being reported.
Field Name: ADAWSUSC
This is an exception field.
- SER.TASK SWTCH - AVERAGE TIME/ELAPSED TIME
- The accumulated waiting time due to a synchronous execution unit switching to DB2 services from the thread being reported. It includes:
- Open/close data set
- SYSLGRNG or SYSLGRNX update
- Commit phase 2
- Dataspace manager services
- Define data set
- Extend data set
- Delete data set
- Log I/Os for commit and abort processing
Special Considerations:- There are no service waits associated with commit phase 2 under read-only threads originating from CICS or IMS. There is a service wait for any thread doing commit phase 2 after an update.
- There is no overlap between the elapsed time reported in this field and the other class 3 elapsed times.
Field Name: ADSTSUST
This is an exception field.
- SER.TASK SWTCH - AV.EVENT/EVENTS
The total number of suspensions due to a synchronous execution unit switching to DB2 services from the thread being reported.
Field Name: ADSTSUSC
This is an exception field.
- UPDATE COMMIT - AVERAGE TIME/ELAPSED TIME
The accumulated wait time because of synchronous execution unit switch for DB2 Phase 2 commit, abort, or deallocation. This includes wait time for Phase 2 commit Log writes and database writes for LOB with LOG NO. For data sharing environment Page P-locks unlocks for updated pages and GBP writes.
Field Name: QWACAWTE
- UPDATE COMMIT - AV.EVENT/EVENTS
The number of wait trace events processed for waits for synchronous execution unit switching for commit or abort.
This value is an average.
Field Name: ADSTARNS
- OPEN/CLOSE - AVERAGE TIME/ELAPSED TIME
Accumulated waiting time for a synchronous execution unit switch to the DB2 OPEN/CLOSE data set service for the HSM recall service.
This value is an average.
Field Name: QWAXOCSE
- OPEN/CLOSE - AV.EVENT/EVENTS
The number of wait trace events processed for waits for synchronous execution unit switching to the open/close service.
This value is an average.
Field Name: ADOCSUSC
- SYSLGRNG REC - AVERAGE TIME/ELAPSED TIME
Accumulated wait time for a synchronous execution unit switch to the DB2 SYSLGRNG recording service. This service is sometimes used for Level ID checking for downlevel detection.
This value is an average.
Field Name: QWAXSLSE
- SYSLGRNG REC - AV.EVENT/EVENTS
The number of wait trace events processed for waits for synchronous execution unit switching to the SYSLGRNG recording service.
This value is an average.
Field Name: ADSLSUSC
- EXT/DEL/DEF - AVERAGE TIME/ELAPSED TIME
Accumulated wait time for a synchronous execution unit switch to the DB2 data space manager services. This includes DEFINE DATA SET, EXTEND DATA SET, DELETE DATA SET, RESET DATA SET, and VSAM CATALOG ACCESS.
This value is an average.
Field Name: QWAXDSSE
- EXT/DEL/DEF - AV.EVENT/EVENTS
The number of wait trace events processed for waits for synchronous execution unit switching to the data space manager service tasks.
This value is an average.
Field Name: ADDSSUSC
- OTHER SERVICE - AVERAGE TIME/ELAPSED TIME
- Could be due to a VSAM catalog update.
In the distributed environment,
it includes the waiting time for the response from the server system.
Performance trace for IFCID 46 to 50, 170, and 171
provide more detailed information for analysis.
Field Name: QWAXOTSE
- OTHER SERVICE - AV.EVENT/EVENTS
The number of wait trace events processed for waits for synchronous execution unit switching to other service tasks.
This value is an average.
Field Name: ADOTSUSC
- ARC.LOG(QUIES) - AVERAGE TIME/ELAPSED TIME
The accumulated waiting time due to the processing of ARCHIVE LOG MODE(QUIESCE) commands.
This time does not represent the time required to perform the entire command.
Field Name: QWAXALOG
This is an exception field.
- ARC.LOG(QUIES) - AV.EVENT/EVENTS
The total number of suspensions due to the processing of ARCHIVE LOG MODE(QUIESCE) commands.
This counter belongs to class 1 (not to class 3 like the rest of the fields in this section) but it is shown here to be adjacent to the archive log quiesce suspension time, which is in class 3.
Field Name: ADALSUSC
This is an exception field.
- LOG READ - AVERAGE TIME/ELAPSED TIME
- The accumulated wait time for:
- Archive Log reads
- Active Log reads
- Active Log prefetch reads
- Fast Log apply log reads
Field Name: QWAXAWAR
- LOG READ - AV.EVENT/EVENTS
The number of wait trace events processed for archive reads, active reads, and active log prefetch reads.
Field Name: ADLRSUSC
This is an exception field.
- DRAIN LOCK - AVERAGE TIME/ELAPSED TIME
The accumulated waiting time for a drain lock. This is the time the requester is suspended while waiting to acquire the drain lock.
Field Name: QWAXAWDR
This is an exception field.
- DRAIN LOCK - AV.EVENT/EVENTS
The total number of suspensions due to drain lock processing.
Field Name: ADDRSUSC
This is an exception field.
- CLAIM RELEASE - AVERAGE TIME/ELAPSED TIME
The accumulated waiting time for a drain waiting for claims to be released. After the drain lock is acquired, the drainer must wait for claim holders to release the object.
Field Name: QWAXAWCL
This is an exception field.
- CLAIM RELEASE - AV.EVENT/EVENTS
The total number of suspensions until the claims are released.
Field Name: ADCMSUSC
This is an exception field.
- PAGE LATCH - AVERAGE TIME/ELAPSED TIME
- Page latch suspension could be due to concurrent threads that
try to update a hot page that is frequently written
because of a low deferred write threshold.In the data sharing environment, within the same member,
the first thread gets a P-lock (such as: Index leaf page P-Lock
or P-Lock for Space map page or data page P-lock for Row level
locking) during high INSERT activity.
Performance trace for IFCID 226 and 227 provide more information
for detailed analysis.With a high number of concurrent threads,
for subsequent threads in the same member for the same
resource, contention is reported as encountering a
page latch contention.
Randomizing the Index key helps minimizing page
latch contentions
for the Index leaf page.If the page latch is for a space map page and an
incremental image copy is not used, use the
DDL TRACKMOD NO option to avoid frequent updates
to the space map page.
The Member Cluster option reduces page latch contention
for a space map page.
Field Name: QWACAWTP
- PAGE LATCH - AV.EVENT/EVENTS
The total number of suspensions due to page latch contentions.
Field Name: ADPGSUSC
- NOTIFY MSGS - AVERAGE TIME/ELAPSED TIME
The accumulated elapsed waiting time due to suspensions caused by sending notify messages to other members in the data sharing group. Messages are sent, for example, when the database descriptors are changed due to DDL.
Field Name: QWACAWTG
- NOTIFY MSGS - AV.EVENT/EVENTS
The number of suspensions caused by sending messages to other members in the data sharing group. This value is only calculated if accounting class 3 is active and DB2 is a member of a data sharing group.
Field Name: ADNOSUSC
- GLOBAL CONTENTION - AVERAGE TIME/ELAPSED TIME
The total accumulated waiting time caused by the suspension of IRLM lock requests due to global lock contention in a data sharing environment that require intersystem communication to resolve.
Look at the Accounting section that shows
Parent/Child/Other break down for the L-Lock
and P-Lock Global contentions.
Also look at the GBP Buffer Pool statistics Page P-Lock suspensions
and negotiations category
(Space map page / Data page / Index leaf page)
in the Statistics report for the same time interval:- If the majority of the negotiations are for the space map pages or data pages, the Member Cluster option can help.
- If the majority of the negotiations are for data pages, consider to change small tables with row level locking to page level locking with MAXROWS 1.
- If the majority of the negotiations are for Index leaf pages, consider adding more free space (PCTFREE / FREEPAGE) and/or minimizing the index key size for a unique or semi-unique multi-column index.
Field Name: ADGCSUST
- GLOBAL CONTENTION - AV.EVENT/EVENTS
The number of suspensions caused by global lock contention. This value is only calculated if accounting class 3 is active and DB2 is a member of a data sharing group.
Field Name: ADGCSUSC
- COMMIT PH1 WRITE I/O - AVERAGE TIME/ELAPSED TIME
The accumulated time waiting for phase 1 commit write I/O. An example for this suspension is LOB Table Space with LOG NO Phase 1 commit database synchronous write I/O processing.
Field Name: QWAXAWFC
- COMMIT PH1 WRITE I/O - AV.EVENT/EVENTS
The total number of wait trace events for commit phase 1 I/O.
Field Name: ADFCSUSC
- ASYNCH CF REQUESTS - AVERAGE TIME/ELAPSED TIME
- The accumulated wait time for IXLCACHE and IXLFCOMP requests.
Field Name: QWAXIXLT
- ASYNCH CF REQUESTS - AV.EVENT/EVENTS
The number of IXLCACHE and IXLFCOMP asynchronous requests.
Field Name: ADIXSUSC
- TCP/IP LOB XML - AVERAGE TIME/ELAPSED TIME
The accumulated wait time for TCP/IP LOB and XML (storing large object and XML) materialization.
Field Name: QWACALBW
- TCP/IP LOB XML - AV.EVENT/EVENTS
The number of wait trace events processed for waits for TCP/IP LOB and XML materialization.
Field Name: ADLMSUSC
- ACCELERATOR - AVERAGE TIME/ELAPSED TIME
The accumulated wait time for requests to an accelerator.
Field Name: QWACAACW
- ACCELERATOR - AV.EVENT/EVENTS
The total number of suspensions due to a request to an accelerator.
Field Name: ADAASUSC
- AUTONOMOUS PROCEDURE - AVERAGE TIME/ELAPSED TIME
The accumulated time waiting for autonomous procedures to complete.
Field Name: AATXSUST
- AUTONOMOUS PROCEDURE - AV.EVENT/EVENTS
The number of autonomous procedures that were executed:
- For non-rollup records, this value is the number of autonomous procedures that were executed.
- For a parallel query rollup record, this value is 0.
- For a DDF or RRSAF rollup record, this value is the number of autonomous procedures that were executed. These procedures are NOT counted in QWACPCNT.
- For autonomous procedures rollup records, this value is 0.
Field Name: AATCOUNT
- PQ SYNCHRONIZATION - AVERAGE TIME/ELAPSED TIME
The accumulated time waiting for parallel queries to synchronize between parent and child tasks.
Field Name: AWPQSST
- PQ SYNCHRONIZATION - AV.EVENT/EVENTS
The number of times the parallel query processing had to suspend because it was waiting for the synchronization of parent or child.
Field Name: AWPQSSC
- LOB COMPRESSION - AVERAGE TIME/ELAPSED TIME
- The accumulated time waiting for a
compression of DB2 large objects (LOB)
(DB2 field QWAX_LOBCOMP_WAIT).
Field Name: AWLCSUST
- LOB COMPRESSION - AV.EVENT/EVENTS
- The number of wait trace events
processed for DB2 large object (LOB) compressions
(DB2 field QWAX_LOBCOMP_COUNT).
Field Name: AWLCSUSC
- FAST INSERT PIPE - AVERAGE TIME/ELAPSED TIME
- The accumulated wait time for pipe wait (DB2 field QWAX_PIPE_WAIT).
Field Name: AWPISUST
- FAST INSERT PIPE - AV.EVENT/EVENTS
- The number of wait trace events that were processed for pipe wait
(DB2 field QWAX_PIPEWAIT_COUNT / 2).
Field Name: AWPISUSC
- TOTAL CLASS 3 - AVERAGE TIME/ELAPSED TIME
The waiting time for all types of class 3 suspensions by the originating task and parallel tasks, if parallelism is employed.
Field Name: ADTSUST
This is an exception field.
- TOTAL CLASS 3 - AV.EVENT/EVENTS
The total number of class 3 suspensions.
Field Name: ADTSUSC
This is an exception field.