Performance Guidelines
If virtual machine assist is available on a processor, the operator
can turn the function off, and on again, for the entireVM/310 system.
Also, if the function is available toVM/310, each virtual machine
operator can turn the function off, and on again, for his own virtual
machine.When you create your VM/370 directory, you can set off the SVC-handling portion of the virtual machine assist function for various
virtual machines by specifyingSVCOFF on the OPTION control statement. VM/370 EXTENDED CONTROL-PROGRAM SUPPORT V"/370 Extended control-Program Support is a
that provides support over and above that
machine assist feature described previously,VM/370's real supervisor state time needed to VM/370 Extended Control-Program Support
functions.• virtual machine assist • CP assist • Virtual interval timer assist
hardware assist function
provided by the virtual
and consequently reduces
support virtual machines.
provides the followingWhenever VM/370 is loaded on one of the supported processors, all three
hardware assist functions plus virtual machine assist are activated
unless turned off by the system operator.
Expanded virtual machine assist includes a more comprehensive
emulation of theSSM, LPSW, STNSK, and STOSM privileged instructions.
Additional privileged instructions are also emulated.CP assist provides a hardware assist for the high-use portions of the
followingCP functions: • Virtual machine I/O • Storage management • Page management • SVC handler • Privileged instruction handler • Dispatcher
If (1)CP assist is turned off, (2) hardware assist does not support the
specific service required, or (3) an error condition occurs, the
appropriateCP software routine is used. Virtual interval timer assist provides for hardware updating of the
location80 interval timer for each virtual machine that has the virtual
timer assist function turned on. This timer assist provides a more
accurate and repeatable interval timer value for virtual machines than
was previously possible throughCP software.
Both virtual machine assist and expanded virtual machine assist are
automatically turned off if the user invokes certain TRACE functions.
In addition, virtual interval timer assist is turned off if external
interrupts are traced.When the tracing function is terminated, CP automatically reactivates these V"/370 hardware assist functions.
For more details onVK/370 Extended control-Program Support, refer to
theQyide. 1A VM/370 Planning and System Generation Guide
If virtual machine assist is available on a processor, the operator
can turn the function off, and on again, for the entire
Also, if the function is available to
operator can turn the function off, and on again, for his own virtual
machine.
virtual machines by specifying
that provides support over and above that
machine assist feature described previously,
functions.
hardware assist function
provided by the virtual
and consequently reduces
support virtual machines.
provides the following
hardware assist functions plus virtual machine assist are activated
unless turned off by the system operator.
Expanded virtual machine assist includes a more comprehensive
emulation of the
Additional privileged instructions are also emulated.
following
If (1)
specific service required, or (3) an error condition occurs, the
appropriate
location
timer assist function turned on. This timer assist provides a more
accurate and repeatable interval timer value for virtual machines than
was previously possible through
Both virtual machine assist and expanded virtual machine assist are
automatically turned off if the user invokes certain TRACE functions.
In addition, virtual interval timer assist is turned off if external
interrupts are traced.
For more details on
the