z/VM 6.3 and the z13 exploitation SPE APAR VM65586

Edit online

When starting analyzing the various waits in relation with dispatching virtual CPUs, we found that a beneficial side effect of the APAR VM65586 - which is intended to enable the Simultaneous Multithreading (SMT) feature for z/VM® 6.3 on IBM® z13 - is also of interest for non-SMT z Systems machines.

Figure 1 compares the total workload throughput of the z/VM 6.3 RSU (recommended service upgrade) 1401 release with the SPE APAR VM65586.
Figure 1. Comparison of total workload throughput for z/VM 6.3 RSU 1401 release with SPE APAR VM65586

This figure is a graphical representation of the information just described.

The use of the SPE APAR VM65586 improved the throughput of the total workload mix by plus 8.6%.

Figure 2 compares the LPAR CPU load of the z/VM 6.3 RSU 1401 release with the SPE APAR VM65586.
Figure 2. Comparison of LPAR CPU load for z/VM 6.3 RSU 1401 release with SPE APAR VM65586

This figure is a graphical representation of the information just described.

The use of the SPE APAR VM65586 reduced the CPU load of the total workload mix by 3.5%, which in this case was almost the equivalent of an entire IFL (0.92 IFL).

Conclusion:

The APAR VM65586 provides changes in CPU and scheduler management that are also advantageous for the zEnterprise 196 system, which does not support SMT. We observed a significant increase in throughput and at reduced CPU cost.