Method and apparatus to control priority preemption of tasks
First Claim
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1. A computer implemented method for controlling preemption rates, the computer implemented method comprising:
- responsive to a plurality of processes being executed by a processor, determining a preemption interval, wherein the preemption interval is a minimum time interval before a priority preemption of a currently running process by a higher priority process occurs;
subtracting a last preemption time from a current time to determine a current time interval, wherein the current time interval is an interval of time since a most recently performed priority preemption of a process took place;
determining whether the preemption interval has expired, wherein the preemption interval has expired if the current time interval is greater than or equal to the preemption interval;
preempting the currently running process in response to a determination that the preemption interval has expired, wherein the preemption interval is adjusted upon determining that adjusting the preemption interval will reduce time in executing processes; and
responsive to performing the priority preemption, setting the last preemption time as the current time, wherein the last preemption time is a time at which the most recently performed priority preemption of a process took place.
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Abstract
A computer implemented method, apparatus, system, and computer usable program product for controlling preemption rates. A scheduler identifies a preemption interval in response to a plurality of processes being executed by a processor. Only a single preemption of a process occurs during the preemption interval. The scheduler preempts a currently running process only once during the preemption interval. The preemption interval is adjusted to increase performance in executing processes.
18 Citations
18 Claims
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1. A computer implemented method for controlling preemption rates, the computer implemented method comprising:
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responsive to a plurality of processes being executed by a processor, determining a preemption interval, wherein the preemption interval is a minimum time interval before a priority preemption of a currently running process by a higher priority process occurs; subtracting a last preemption time from a current time to determine a current time interval, wherein the current time interval is an interval of time since a most recently performed priority preemption of a process took place; determining whether the preemption interval has expired, wherein the preemption interval has expired if the current time interval is greater than or equal to the preemption interval; preempting the currently running process in response to a determination that the preemption interval has expired, wherein the preemption interval is adjusted upon determining that adjusting the preemption interval will reduce time in executing processes; and responsive to performing the priority preemption, setting the last preemption time as the current time, wherein the last preemption time is a time at which the most recently performed priority preemption of a process took place. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An apparatus for controlling preemption rates, the apparatus comprising:
a computer comprising; a storage device connected to a bus, wherein the storage device contains a computer usable program product; and a processor, wherein the processor unit executes the computer usable program code to determine a preemption interval in response to a plurality of processes being executed by a processor, wherein the preemption interval is a minimum time interval before a priority preemption of a currently running process by a higher priority process occurs;
wherein the processor subtracts a last preemption time from a current time to determine a current time interval, wherein the current time interval is an interval of time since a most recently performed priority preemption of a process took place;
wherein the processor determines whether the preemption interval has expired, wherein the preemption interval has expired if the current time interval is greater than or equal to the preemption interval;
wherein the processor preempts a currently running process in response to a determination that the preemption interval has expired, wherein the preemption interval is adjusted upon determining that adjusting the preemption interval will reduce time in executing processes; and
wherein responsive to performing the priority preemption, the processor sets the last preemption time as the current time, wherein the last preemption time is a time at which the most recently performed priority preemption of a process took place.
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12. A computer program product comprising:
a computer readable medium including computer usable program code for controlling preemption rates, said computer program product comprising; computer usable program code for determining a preemption interval, wherein the preemption interval is a minimum time interval before a priority preemption of a currently running process by a higher priority process occurs, in response to a plurality of processes being executed by a processor; computer usable program code for subtracting a last preemption time from a current time to determine a current time interval, wherein the current time interval is an interval of time since a most recently performed priority preemption of a process took place; computer usable program code for determining whether the preemption interval has expired, wherein the preemption interval is expired if the current time interval is greater than or equal to the preemption interval; computer usable program code for preempting the currently running process in response to a determination that the preemption interval has expired, wherein the preemption interval is adjusted upon determining that adjusting the preemption interval will reduce time in executing processes; and computer usable program code for responsive to performing the priority preemption, setting the last preemption time as the current time, wherein the last preemption time is a time at which the most recently performed priority preemption of a process took place. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A system for controlling preemption rates, the system comprising:
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a processor, wherein the processor is executing a process in a plurality of processes waiting to be executed to form a currently running process; and a scheduler, wherein the scheduler determines a preemption interval and preempts the currently running process, wherein the preemption interval is a minimum time interval before a priority preemption of the currently running process by a higher priority process occurs, wherein the scheduler subtracts a last preemption time from a current time to determine a current time interval, wherein the current time interval is an interval of time since a most recently performed priority preemption of a process took place;
wherein the scheduler determines whether the preemption interval has expired, wherein the preemption interval has expired if the current time interval is greater than or equal to the preemption interval;
wherein the currently running process is preempted in response to a determination that the preemption interval has expired, and wherein the preemption interval is adjusted upon determining that adjusting the preemption interval will reduce time in executing processes, and wherein responsive to performing the priority preemption, the scheduler sets the last preemption time as the current time, wherein the last preemption time is a time at which the most recently performed priority preemption of a process took place.
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Specification