Pages that are temporarily locked in real storage are not available
or pageable. Paging proceeds using demand paging to select the best
page for swapping. The reserved page option gives a particular virtual machine an essentially private set of pages. The pages are not locked;
they can be swapped, but normally only for the virtual machine for which
they are reserved. You specify the number of reserved pages for the virtual machine as a maxi.a._ ehen the page selection routine selects an available page for a reserved user, it marks that page reserved if
the maximum specified for the user has not previously been reached. If CP encounters an available (idle) reserved page for the reserved user
during page selection, it is used whether or not the maximum bas been
reached. Only an operator with privilege
reserved pages. Issue the CP SET format: SET RESERVE userid xx class A can specify the RESERVE co •• and in the number of
following
userid is the name of the V"/310 user to whose virtual machine you
are to assign the reserved page option. xx is the maximum number of pages you assign.
If the CP page selection routine cannot locate an available page for
other users because they are all reserved, the routine uses one of the
reserved pages as a last resort. FAYORED EXECUTION OPTION The favored execution option guarantees that a particular virtual machine gets up to a fixed percentage of processor time. Favored in
this sense means that CP provides execution time up to the specified
percentage to that virtual machine, that virtual machine can
use that much processor time. At regular time intervals, the CP dispatcher checks the processor time used by the favored virtual machine. If the guaranteed percentage is exceeded, the machine gets its normal priority for the remainder of the time interval. If the
percentage used is less than the guaranteed value, the favored virtual machine has the highest execution priority until it reaches that
threshold. You, as the system oFerator with privilege class A, specify
the percentage of processor time assured by the favored option in the CP SET command. The format of the command is: r , SET FAVORED userid 'xx I 10FFI L userid is the name of the V"/310 user whose virtual machine is to
be assigned the favored option xx is any percentage value from 1 to 99 OFF operand stops favored operation.
28 VH/370 Operator's Guide

You can assign multiple virtual machines the favored execution option only one virtual machine at a time can be assigned a specified favored
percentage value.
set favored operatns 75
set favored payroll
set favored revenue
set favored hot jobs VIRTUAL=REAL OPTION The virtual=real option permanently relocates the CP nucleus (except for
real page 0) to provide space in real lower storage to contain the
largest virtual=real machine. For the virtual machine, each page froa
page 1 to its last or page is in its true real storage location; only its page zero is relocated. The virtual machine still runs in
relocate mode, but because each virtual page frame address is the same as the real page frame address, the virtual machine requires no CCW translation for the virtual machine. Because no CCW translation is DO check is made of the I/O data addresses. The virtual
machine must ensure that no I/O data transfer occurs into real page zero
or beyond the upper boundary of the virtual aachine's storage. Failure
to observe these limits can cause daaage to the VM/370 systea or to
other virtual machines. Initial program loading of a named or shared systea is not allowed in
the virtual=real machine; the hexadeciaal device address must be used. Several aspects of the operation of the virtual=real option can
affec't overall system operation:
1. The area of contiguous storage built for the virtual=real machine must be large enough to contain the entire addressing space of the
largest virtual=real .achine. 2. Only virtual machines with the virtual=real option can use the real
storage reserved for virtual=real machines. Only one virtual=real virtual machine can run at a time. The storage is not available
for other users, nor for VM/370 use, unless the virtual=real
machine is not logged on and you issue an UNLOCK command with the VIRT=REAL option. When you this command, all page frames previously reserved for the virtual=real machine are permanently
relinquished to the available-page pool. Once these virtual=real
page frames are available to the page pool, no virtual=real machine can run until you load VM/370 again (via IPt). For this reason, it
is suggested that the virtual=real aachine should machine with
high availability and heavy workload deaandso It possible
to relinquish only soae of the virtual=real page frames (if, for
exaaple, a smaller virtual=real aachine is to be run). All
virtual=real page fraaes are locked until all are released to the
pool. Section 2. Initiating VM/370 Operation 29