Evaluating the zIIP Feature Benefits

Document ID : KB000025093
Last Modified Date : 14/02/2018
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Description:

Evaluation of the zIIP feature requires neither zIIP processors nor even hardware that is capable of supporting zIIP processors. Use these steps to determine the benefits that can be achieved by using the zIIP feature.

Solution:

Several easy steps are used to determine the benefits that can be achieved by using the zIIP feature as follows:

  1. Run CV with ZIIP=N and record the results of DCMT DISPLAY SUBTASK EFFECTIVENESS.
  2. Run CV with ZIIP=Y and record the results of DCMT DISPLAY SUBTASK EFFECTIVENESS.
  3. Compare the Total CPU time TCB column from Step 1 with that from Step 2. The difference is proportional to the potential reduction in both the total CPU use and the Total Cost of Ownership (TCO) that can be achieved by using the zIIP feature.

The SRB column from Step 2 is proportional to the number of MIPs of zIIP processing power that will be required to achieve these cost reductions

Examples

The following displays indicate that each run used between 93.5108 and 98.3110 CPU seconds of total normalized CPU.

The second run shows that 91.1222 CPU seconds out of a total of 93.5108 CPU seconds were offloaded to an SRB. Approximately one third of this SRB CPU time can be offloaded to a zIIP processor. For this particular application mix, approximately one third of the total CV CPU could be offloaded to zIIP processors.

Since a zIIP processor was present, the actual offloaded CPU can then be confirmed from the JES LOG Step End messages, IEF374I, which, in this case, indicates a total CPU reduction of 31.68 seconds.

Step 1 Output with ZIIP=N

NOTE: The Total CPU Time 98.3110 seconds is the sum of the TCB (00:01:38.3110)

+----------------------------------------------------------------------------------+
?                                                                                  ?
? *** Subtask display ***                                                          ?
? Subtask          Elapsed time                  Total CPU time         % CPU  SRB ?
?  Name         TCB            SRB            TCB            SRB       TCB SRB     ?
? -------- -------------- -------------- -------------- -------------- --- ---     ?
? MAINTASK  00:00:14.0505  00:00:00.0000  00:00:02.3699  00:00:00.0000  16 N/A  N  ?
? SUBT0001  00:00:00.0122  00:00:00.0000  00:00:00.0104  00:00:00.0000  85 N/A  N  ?
? SUBT0002  00:00:00.0175  00:00:00.0000  00:00:00.0131  00:00:00.0000  74 N/A  N  ?
? SUBT0003  00:00:00.2348  00:00:00.0000  00:00:00.0398  00:00:00.0000  16 N/A  N  ?
? SUBT0004  00:00:00.2175  00:00:00.0000  00:00:00.0240  00:00:00.0000  11 N/A  N  ?
? SUBT0005  00:01:42.0081  00:00:00.0000  00:01:35.8538  00:00:00.0000  93 N/A  N  ?
? -------- -------------- -------------- -------------- -------------- --- ---     ?
? Totals    00:01:56.5406  00:00:00.0000  00:01:38.3110  00:00:00.0000  84 N/A     ?
?                                                                                  ?
+----------------------------------------------------------------------------------+

JES LOG Step End Message
+----------------------------------------------------------------------------------+
? IEF374I STEP/DCV     /STOP  2008242.0425 CPU    1MIN 39.53SEC SRB                ?
? 0MIN 11.73SEC VIRT  7840K SYS   552K EXT   56072K SYS   11460K                   ?
+----------------------------------------------------------------------------------+
NOTE:   CPU 1MIN 39.53SEC + SRB 0MIN 11.73SEC = 111.26SEC

Step 2 Output with ZIIP=Y

NOTE: The amount of CPU seconds that was offloaded to an SRB is 91.1222.
The Total CPU Time 93.5108 is the sum of the TCB (00:00:02.3886) and

SRB (00:01:31.1222) added together.

To calculate the amount of CPU seconds that were offloaded to an SRB subtract the total TCB (00:00:02.3886) from the Total CPU Time (93.5108).


+----------------------------------------------------------------------------------+
?                                                                                  ?
? *** Subtask display ***                                                          ?
? Subtask          Elapsed time                  Total CPU time         % CPU  SRB ?
?  Name         TCB            SRB            TCB            SRB       TCB SRB     ?
? -------- -------------- -------------- -------------- -------------- --- ---     ?
? MAINTASK  00:00:12.9116  00:00:00.0434  00:00:02.1387  00:00:00.0525  16 120  Y  ?
? SUBT0001  00:00:00.0125  00:00:00.0000  00:00:00.0111  00:00:00.0000  88 N/A  Y  ?
? SUBT0002  00:00:00.0118  00:00:00.0002  00:00:00.0103  00:00:00.0000  87  00  Y  ?
? SUBT0003  00:00:00.1643  00:00:00.0014  00:00:00.0624  00:00:00.0016  37 114  Y  ?
? SUBT0004  00:00:00.0276  00:00:00.0004  00:00:00.0239  00:00:00.0008  86 200  Y  ?
? SUBT0005  00:00:00.3849  00:01:17.1037  00:00:00.1422  00:01:31.0673  36 118  Y  ?
? -------- -------------- -------------- -------------- -------------- --- ---     ?
? Totals    00:00:13.5127  00:01:17.1491  00:00:02.3886  00:01:31.1222  17 118     ?
?                                                                                  ?
+----------------------------------------------------------------------------------+

JES LOG Step End Message
+----------------------------------------------------------------------------------+
? IEF374I STEP/DCV     /STOP  2008242.0400 CPU    1MIN 01.60SEC SRB                ?
? 0MIN 17.98SEC VIRT  7840K SYS   552K EXT   56080K SYS   11500K                   ?
+----------------------------------------------------------------------------------+
NOTE: CPU 1MIN 01.60SEC + SRB 0MIN 17.98SEC = 79.58SEC

Subtracting the total offloaded CPU from the STEP2 IEF374I message (79.58), from the total offloaded CPU
from the STEP1 IEF374I message (111.26) indicates a total CPU reduction of 31.68 seconds.