z/VM: CP Planning and Administration - z/VM - IBM

THROTTLETHROTTLE Statement►► THROTtle ▼ rdevrdev1-rdev2RATE nnnnn ►◄PurposeUse the THROTTLE statement to limit (throttle) the number of I/O operations that aguest operating system can initiate to a specific real device. This prevents a guestfrom interfering with or dominating I/O resources.The THROTTLE statement adds real devices to the I/O throttling list. Afterinitialization completes, CP begins limiting (throttling) the guest’s I/O rate to thespecified device or devices.How to SpecifyInclude as many statements as needed; they are optional. You can placeTHROTTLE statements anywhere in the system configuration file. If you specifymore than one statement with the same device number, CP uses the I/O rate onthe last statement, and ignores all previous statements with that device number.Operandsrdevrdev1-rdev2identifies the real device or devices that you want to throttle. The variable rdevis the real device number of the device and must be a hexadecimal numberbetween X'0000' and X'FFFF'. You can specify a single device address, a rangeof device addresses, or any combination thereof.RATE nnnnnspecifies the I/O throttling rate (number of I/O operations per second that thisdevice can process from a guest operating system). The variable nnnnn mustbe a decimal number between 1 and 10,000.UsageNotes1. To add devices to or delete devices from the I/O throttling list after initialization,use the SET THROTTLE command. For more information about the SETTHROTTLE command, see the z/VM: CP Commands and Utilities Reference.2. To display the list of devices being throttled and their respective I/O rates, usethe QUERY THROTTLE command. For more information about the QUERYTHROTTLE command, see the z/VM: CP Commands and Utilities Reference.Examples1. To limit all guest operating systems using 1c10 to 1 I/O operations per second,use the following THROTTLE statement:Throttle 1c10 rate 1 */During initialization, CP responds:Device 1C10 added to throttle set. Rate = 1.236 z/VM: CP Planning and Administration