Dealing with Accounting TIME FIELDS

Document ID : KB000115615
Last Modified Date : 24/09/2018
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Question:
 I have a question about the correspondance between ETIME, WTIME and CTIME when dealing with an accounting table.
May I have ETIME-WTIME=CTIME for 0F type for example? (0F is for DataCom Server). 
Environment:
z/os, CA Datacom/DB 15.0 and higher
Answer:
All these "Times" are duration spent inside the Multi-user (so outside of the server).
Requests coming from Server are processed by the Multi-User.
ETIME - WTIME = RTIME (run time)


- ETIME 
Elapsed time, in microseconds, from the time that the request is received by the Multi-User Facility until it is returned to the user.

- CTIME
Reflects the CPU time, in microseconds, which the Multi-User Facility spent executing the request.
CTIME adds additional operating system overhead. If you do not use this element in any of your Accounting tables, you can reduce this overhead by coding NO for the cpu-time parameter in the ACCTPRM MUF startup option.

- RTIME
Runtime - ETIME (elapsed time) minus WTIME (wait time) in microseconds.
If only runtime is desired, it is not necessary to define ETIME and WTIME.

- WTIME
Total time, in microseconds, that the request had to wait because of exclusive control, I/O, and so forth.

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Other relevant information:
             Differences Between RTIME, CTIME, and ETIME                 
                                                                         
                                                                         
RTIME - Accounts for time the request is actually processed.  It is  inflated by page faults and it continues to accumulate even if   
              the Multi-User Facility has been swapped out.                    
CTIME - Reflects actual CPU time                                         
ETIME - Tracks the time from initiation of a request to completion.  A timestamp is taken at the moment a request starts in Multi-    
              User.  A second timestamp is taken at the moment it finishes.  The difference between these two is called ETIME.                
WTIME - The amount of time a request has to wait during its execution.  It contains waits that are known to Multi-User, e.g., waits for  
               exclusive control and I/O waits.                                 
                                                                         
When WTIME is subtracted from ETIME, RTIME remains.  This is not CPU time.  CTIME (MVS only) comes closest to pure CPU time.  It is RTIME     
minus the "system" waits.                                                
                                                                         
At times, CTIME can be greater than RTIME.  This can occur because Multi-User overhead (index queue processing, accounting processing)      
is included in CTIME.                                                    
                                                                         
ETIME is clocked from the time that Multi-User accepts a request  until that request has completed processing in Multi-User.  Because      
MUF is processing many requests at once, the elapsed time of all  requests in Multi-User at one time are all occurring simultaneously.     
While a task is waiting on I/O or on a higher priority task, instructions are not executing, but time is passing.                            
                                                                         
CTIME represents our best efforts at charging for instruction execution to the request being processed.  Multi-User may have many requests work- 
ing at once, but at one time, only one is executing instructions and therefore, that one is charged.  This will vary depending on the         
workload being done.                                                     
                                                                         
CTIME can be more than ETIME when Multi-User is running on a multi-processor.  Because we have more TCBs in a MUF running and those TCBs    
can be run on separate processors, part of this 'MUF overhead', running under other TCB's than the TCB belonging to the specific task, is        
included in the CTIME for that task.                                     
                                                                         
The CTIME spent ending one request and waiting for the next is charged to the caller on the next call when possible.   
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There is a Video Webcast related to Accounting at the following address:
https://support.ca.com/us/product-content/recommended-reading/technical-document-index/ca-datacom-video-and-recorded-webcast-index.html?intcmp=searchresultclick&resultnum=7?intcmp=searchresultclick&resultnum=7            
Additional Information:
There is a Video Webcast related to Accounting at the following address:
https://support.ca.com/us/product-content/recommended-reading/technical-document-index/ca-datacom-video-and-recorded-webcast-index.html?intcmp=searchresultclick&resultnum=7?intcmp=searchresultclick&resultnum=7