Low overhead I/O interrupt
First Claim
1. An apparatus comprising:
- a processor handling an I/O request in an I/O operation;
main storage controlled by said processor for storing data;
one or more I/O devices for sending data to or receiving data from said main storage in the I/O operation;
a time-of-day (TOD) register for containing a TOD value;
a clock for containing a current TOD value;
a summary register having a first condition when any one of said devices requests an I/O operation and a second condition when no devices have an outstanding I/O request, each device having an outstanding I/O request setting said summary register to its first condition only when said summary register is in said second condition, said device further placing the current TOD value in said TOD register only when changing the summary register from its second condition to its first condition;
a checking program for determining if a specified time delay has been exceeded between the value in said TOD register and the current TOD for each requested I/O operation, said checking program driving an interrupt to said processor when the specified time delay has been exceeded.
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Accused Products
Abstract
An apparatus, method and program product for sending data to or receiving data from one or more I/O devices in an I/O operation with a main storage controlled by a processor in a data processing system. The apparatus includes a time-of-day (TOD) register for containing a TOD value, a clock for containing a current TOD value, and a summary register having a first condition when any one of said devices requests an I/O operation and a second condition when no devices have an outstanding I/O request, each device having an outstanding I/O request sets the summary register to its first condition only when the summary register is in its second condition, and further places the current TOD value in the TOD register. A checking program determines if a specified time delay has been exceeded between the value in said TOD register and the current TOD for each requested I/O operation. The checking program drives an interrupt to the processor when the specified time delay has been exceeded.
99 Citations
28 Claims
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1. An apparatus comprising:
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a processor handling an I/O request in an I/O operation;
main storage controlled by said processor for storing data;
one or more I/O devices for sending data to or receiving data from said main storage in the I/O operation;
a time-of-day (TOD) register for containing a TOD value;
a clock for containing a current TOD value;
a summary register having a first condition when any one of said devices requests an I/O operation and a second condition when no devices have an outstanding I/O request, each device having an outstanding I/O request setting said summary register to its first condition only when said summary register is in said second condition, said device further placing the current TOD value in said TOD register only when changing the summary register from its second condition to its first condition;
a checking program for determining if a specified time delay has been exceeded between the value in said TOD register and the current TOD for each requested I/O operation, said checking program driving an interrupt to said processor when the specified time delay has been exceeded. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An apparatus for use with a data processing system having a processor handling an I/O request in an I/O operation, main storage controlled by the processor for storing data, and one or more I/O devices for sending data to or receiving data from said main storage in the I/O operation, said apparatus comprising;
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a time-of-day (TOD) register for containing a TOD value, a clock for containing a current TOD value;
a summary register having a first condition when any one of said devices requests an I/O operation and a second condition when no devices have an outstanding I/O request, each device having an outstanding I/O request setting said summary register to its first condition only when said summary register is in said second condition, said device further placing the current TOD value in said TOD register only when changing the summary register from its second condition to its first condition;
a checking program for determining if a specified time delay has been exceeded between the value in said TOD register and the current TOD for each requested I/O operation, said checking program driving an interrupt to said processor when the specified time delay has been exceeded. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method for sending data to or receiving data from one or more I/O devices in an I/O operation with a main storage for storing data in a data processing system having a processor controlling the main storage during an I/O request in the I/O operation, the data processing system including a time-of-day (TOD) register for containing a TOD value, a clock providing a current TOD value, and a summary register having a first condition when any one of said devices requests an I/O operation and a second condition when no devices has an outstanding I/O request, each device having an outstanding I/O request setting said summary register to its first condition only when said summary register is in said second condition, said device further placing the current TOD value in said TOD register only when changing the summary register from its second condition to its first condition, said method comprising:
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determining with a checking program if a specified time delay has been exceeded between the value in said TOD register and the current TOD for each requested I/O operation; and
driving an interrupt to said processor when the specified time delay has been exceeded. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. A program product usable with a system for sending data to or receiving data from one or more I/O devices in an I/O operation with a main storage for storing data in a data processing system having a processor controlling the main storage during an I/O request in the I/O operation, the data processing system including a time-of-day (TOD) register for containing a TOD value, a clock providing a current TOD value, and a summary register having a first condition when any one of said devices requests an I/O operation and a second condition when no devices has an outstanding I/O request, each device having an outstanding I/O request setting said summary register to its first condition only when said summary register is in said second condition, said device further placing the current TOD value in said TOD register only when changing the summary register from its second condition to its first condition, said program product comprising:
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A computer readable medium having recorded thereon computer readable program code means for performing the method comprising;
determining with a checking program if a specified time delay has been exceeded between the value in said TOD register and the current TOD for each requested I/O operation; and
its driving an interrupt to said processor when the specified time delay has been exceeded. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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Specification