How can we tell how much CPU we save in an IDMS CV for a specific set of transactions with zIIP enabled?
To measure if zIIP is helping by reducing the CPU TCB time you would need to do something like the following procedure.
1). Bring up your IDMS system with zIIP off.
2). Run your test with a workload that represents your normal workload.
3). At the end of your test issue DCMT D STAT SYS
4). Bring up your IDMS system with zIIP on.
5). Run your test with the same workload that represents your normal workload.
6). At the end of your test issue DCMT D STAT SYS
Note. If your test is only using a small number of transactions and/or for a short period of time then you should issue the DCMT D STAT SYS both just before and just after your test period. Subtract the ending values from the beginning values and used the result in the calculations discussed below.
Using the DCMT D STAT SYS output .
For the test without zIIP being turned on. Add the Total System time and the Tot User time then Divide the result by the number of tasks to get an average of the CPU used.
For the test with zIIP turned on. Add the Tot System Time and the Tot User Time, subtract the zIIP on zIIP time and zIIP on CP time, divide the result by the number of tasks to get an average of CPU used.
Compare the average from both tests. The average with zIIP on will be less than the average with zIIP off. You can calculate the percentage of the benefit using the averages from both tests.
Sample DCMT D STAT SYS shown below.
D STAT SYS
11:10:36.01 18/284 Current Time 00:07.609924 Tot System Time
09:41:17.15 18/283 Startup Time 00:00.000000 Tot User Time
00:05.436893 zIIP on zIIP Time
00:00.107687 zIIP on CP Time
65,936 Number of Swaps
TASKS: 73274 Processed 0 Abended 40 Max Tasks