Reserved device access contention reduction
First Claim
1. A computer program product for reducing reserved device access contention at a control unit in communication with a plurality of operating systems via one or more channels, the computer program product comprising:
- a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising;
receiving a command message at the control unit from a first operating system of the plurality of operating systems via the one or more channels, wherein the command message includes an I/O operation command for a device in communication with the control unit;
receiving a device busy indicator from the device, wherein the device busy indicator notifies the control unit that the device is reserved by a second operating system of the plurality of operating systems;
queuing the command message on a device busy queue in response to the device busy indicator;
initiating a device busy timer in response to queuing the command message on the device busy queue;
monitoring the device for a device end indicator, wherein the device end indicator notifies the control unit that the device is ready to receive a new I/O operation command;
servicing the device busy queue to perform the I/O operation command in response to the device end indicator;
reading a value of the device busy timer in response to servicing the device busy queue to perform the I/O operation command, the reading performed by the control unit; and
outputting the value of the device busy timer in a transport response information unit message to the first operating system via the one or more channels.
1 Assignment
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Accused Products
Abstract
A computer program product, an apparatus, and a method for reducing reserved device access contention at a control unit in communication with a plurality of operating systems via one or more channels are provided. The computer program product includes a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method that includes receiving a command message at the control unit from a first operating system, including an I/O operation command for a device. A device busy indicator is received, indicating that a second operating system has reserved the device. The command message is queued on a device busy queue in response to the device busy indicator. The control unit monitors for a device end indicator. The device busy queue is serviced to perform the I/O operation command in response to the device end indicator.
122 Citations
34 Claims
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1. A computer program product for reducing reserved device access contention at a control unit in communication with a plurality of operating systems via one or more channels, the computer program product comprising:
a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising; receiving a command message at the control unit from a first operating system of the plurality of operating systems via the one or more channels, wherein the command message includes an I/O operation command for a device in communication with the control unit; receiving a device busy indicator from the device, wherein the device busy indicator notifies the control unit that the device is reserved by a second operating system of the plurality of operating systems; queuing the command message on a device busy queue in response to the device busy indicator; initiating a device busy timer in response to queuing the command message on the device busy queue; monitoring the device for a device end indicator, wherein the device end indicator notifies the control unit that the device is ready to receive a new I/O operation command; servicing the device busy queue to perform the I/O operation command in response to the device end indicator; reading a value of the device busy timer in response to servicing the device busy queue to perform the I/O operation command, the reading performed by the control unit; and outputting the value of the device busy timer in a transport response information unit message to the first operating system via the one or more channels. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An apparatus for reducing reserved device access contention, the apparatus comprising:
a control unit in communication with a plurality of operating systems via one or more channels, the control unit configured to perform a method comprising; receiving a command message at the control unit from a first operating system of the plurality of operating systems via the one or more channels, wherein the command message includes an I/O operation command for a device in communication with the control unit; receiving a device busy indicator from the device, wherein the device busy indicator notifies the control unit that the device is reserved by a second operating system of the plurality of operating systems; queuing the command message on a device busy queue in response to the device busy indicator; initiating a device busy timer in response to queuing the command message on the device busy queue; monitoring the device for a device end indicator, wherein the device end indicator notifies the control unit that the device is ready to receive a new I/O operation command; servicing the device busy queue to perform the I/O operation command in response to the device end indicator; reading a value of the device busy timer in response to servicing the device busy queue to perform the I/O operation command; and outputting the value of the device busy timer in a transport response information unit message to the first operating system via the one or more channels. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method for reducing reserved device access contention at a control unit in communication with a plurality of operating systems via one or more channels, the method comprising:
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receiving a command message at the control unit from a first operating system of the plurality of operating systems via the one or more channels, wherein the command message includes an I/O operation command for a device in communication with the control unit; receiving a device busy indicator from the device, wherein the device busy indicator notifies the control unit that the device is reserved by a second operating system of the plurality of operating systems; queuing the command message on a device busy queue in response to the device busy indicator; initiating a device busy timer in response to queuing the command message on the device busy queue; monitoring the device for a device end indicator, wherein the device end indicator notifies the control unit that the device is ready to receive a new I/O operation command; servicing the device busy queue to perform the I/O operation command in response to the device end indicator; reading a value of the device busy timer in response to servicing the device busy queue to perform the I/O operation command, the reading performed by the control unit; and outputting the value of the device busy timer in a transport response information unit message to the first operating system via the one or more channels. - View Dependent Claims (16, 17, 18)
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19. A computer program product for reducing reserved device access contention at a control unit in communication with a plurality of operating systems via one or more channels, the computer program product comprising:
a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising; receiving a command message at the control unit from a first operating system of the plurality of operating systems via the one or more channels, wherein the command message includes an I/O operation for a device in communication with the control unit; responsive to determining by the control unit that the device is busy, performing a) through f) by the control unit, the device being busy indicating that the device is reserved by a second operating system of the plurality of operating systems; a) queuing the I/O operation on a device busy queue; b) initiating a device busy timer; c) determining that the device is no longer busy, the device no longer being busy indicating that the device is ready to receive a new I/O operation; d) servicing the device busy queue to perform the I/O operation in response to the determination that the device is no longer busy; e) reading a value of the device busy timer in response to the servicing the device busy queue; and f) outputting the value of the device busy timer to the first operating system via the one or more channels. - View Dependent Claims (20, 21, 22, 23)
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24. An apparatus for reducing reserved device access contention, the apparatus comprising:
a control unit configured to communicate with a plurality of operating systems via one or more channels, the control unit configured to communicate with a device, the control unit configured to perform a method comprising; receiving a command message at the control unit from a first operating system of the plurality of operating systems via the one or more channels, wherein the command message includes an I/O operation for the device in communication with the control unit; responsive to determining by the control unit that the device is busy, performing a) through f), the device being busy indicating that the device is reserved by a second operating system of the plurality of operating systems; a) queuing the I/O operation on a device busy queue; b) initiating a device busy timer; c) determining that the device is no longer busy, the device no longer being busy indicating that the device is ready to receive a new I/O operation; d) servicing the device busy queue to perform the I/O operation in response to the determination that the device is no longer busy; e) reading a value of the device busy timer in response to the servicing the device busy queue; and f) outputting the value of the device busy timer to the first operating system via the one or more channels. - View Dependent Claims (25, 26, 27, 28, 29)
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30. A method for reducing reserved device access contention at a control unit in communication with a plurality of operating systems via one or more channels, the method comprising:
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receiving a command message at the control unit from a first operating system of the plurality of operating systems via the one or more channels, wherein the command message includes an I/O operation for a device in communication with the control unit; responsive to determining by the control unit that the device is busy, performing a) through f) by the control unit, the device being busy indicating that the device is reserved by a second operating system of the plurality of operating systems; a) queuing the I/O operation on a device busy queue; b) initiating a device busy timer; c) determining that the device is no longer busy, the device no longer being busy indicating that the device is ready to receive a new I/O operation; d) servicing the device busy queue to perform the I/O operation in response to the determination that the device is no longer busy; e) reading a value of the device busy timer in response to the servicing the device busy queue; and f) outputting the value of the device busy timer to the first operating system via the one or more channels. - View Dependent Claims (31, 32, 33, 34)
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Specification