IBM z13s, Technical Manual

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IBM z13s Technical Guide
When PROCVIEW CORE or CORE,CPU_OK are specified in z/OS running in z13s, HiperDispatch is
forced to run as enabled. You cannot disable it.The PROCVIEW statement cannot be changed
dynamically, so you must run an IPL after changing it to make the new setting effective.
The
MT_ZIIP_MODE
parameter in the IEAOPTxx controls zIIP SMT mode. This parameter can
be
1
(the default), where only one thread can be running in a core, or
2
, where up two threads
can be running in a core. If
PROCVIEW CPU
is specified, the
MT_ZIIP_MODE
is always
1
.
Otherwise, the use of SMT to dispatch two threads in a single zIIP logical processor
(
MT_ZIIP_MODE=2
) can be changed dynamically by using the
SET OPT=xx
setting in the
IEAOPTxx parmlib. Changing the MT mode for all cores can take some time to complete.
The activation of SMT mode also requires that the HMC Customize/Delete Activation Profiles
task, “Do not end the time slice if a partition enters a wait state”, must not be selected. This is
the recommended default setting.
PROCVIEW COR E requires DISPLAY M=CORE and CONFIG CORE to display the core states and
configure an entire core.
Figure 7-1 shows the result of the display core command with processor view core and SMT
enabled.
Figure 7-1 Result of the display core command
The use of SMT in z/VM V6R3
6
requires the application of a small programming
enhancement (SPE) that has a new MULTITHREADING statement in the system configuration
file, has HiperDispatch enabled, and has the dispatcher work distribution mode set to
reshuffle
.
6
The z/VM 6.3 SMT enablement APAR is VM65586.