z/VM: CP Commands and Utilities Reference - z/VM - IBM

Usage Notes
SPecial
tells CP to change the hot I/O rate for all the special devices (3088s, CTCAs,
37x5s) in the active I/O configuration.
SWCH
SWitch
tells CP to change the hot I/O rate for all the switching devices in the active I/O
configuration.
TApe
tells CP to change the hot I/O rate for all the tape drive devices in the active I/O
configuration.
TErminal
tells CP to change the hot I/O rate for all the terminals in the active I/O
configuration.
Unit_record
UR
tells CP to change the hot I/O rate for all the unit record devices in the active
I/O configuration.
Default
tells CP to use the default rate of 16 unsolicited interrupts per second for the
specified device or devices.
Off
turns hot I/O detection off and tells CP to accept all unsolicited interrupts for the
specified device or devices.
Warning!
We do not recommend that you specify the OFF operand to turn off the hot
I/O detection for a device or devices for any length of time. Hot I/O detection
protects CP from broken hardware that floods the system with unsolicited
interrupts. If you turn hot I/O detection off, you may experience performance
degradation or a system abend.
nnnnn
tells CP how many unsolicited interrupts per second to accept for the specified
device or devices before CP stops accepting input from the device or devices.
The variable nnnnn is a decimal number from 1 to 62500.
1. CP processes SET HOTIO commands in the order that you enter them. If you
enter more than one SET HOTIO command for a specific device or devices, the
last command you enter is the one that CP uses for that device or devices. For
example, if you issued the following commands:
set hotio all 25
set hotio 2ff 50
set hotio switch 75
SET HOTIO
CP sets the hot I/O rate for all devices in the active I/O configuration to 25, then
CP sets the hot I/O rate for device X'2FF' to 50, and lastly, CP sets the hot I/O
rate for all special switching devices to 75. If device X'2FF' is a special
switching device, the third command overrides the second command and CP
sets the hot I/O rate for device X'2FF' to 75, instead of 50.
Chapter 2. CP Commands 1255