IP Library Granted Patent US 9,361,155
Granted Patent B2
US 9,361,155 · App. 14/839,439 · Granted Jun 7, 2016

Time critical tasks scheduling

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Quick Facts
Patent No.
US 9,361,155
App. No.
14/839,439
Granted
Jun 7, 2016
Kind
B2
Abstract

A method and system for scheduling a time critical task. The system may include a processing unit, a hardware assist scheduler, and a memory coupled to both the processing unit and the hardware assist scheduler. The method may include receiving timing information for executing the time critical task, the time critical task executing program instructions via a thread on a core of a processing unit and scheduling the time critical task based on the received timing information. The method may further include programming a lateness timer, waiting for a wakeup time to obtain and notifying the processing unit of the scheduling. Additionally, the method may include executing, on the core of the processing unit, the time critical task in accordance with the scheduling, monitoring the lateness timer, and asserting a thread execution interrupt in response to the lateness timer expiring, thereby suspending execution of the time critical task.

Claims (71)

1. A method for monitoring a time critical task, the method comprising:

determining a schedule for the time critical task based on received timing information, wherein the time critical task executes program instructions via a thread on a core of a processing unit, wherein the time critical task is a function of the overall thread deadline and a specified thread bandwidth, and wherein said determining comprises determining a wakeup time, a thread cycle time, and an overall thread deadline;

executing, on the core of the processing unit, the time critical task in accordance with the schedule; and

suspending execution of the time critical task via assertion of a thread interrupt in response to a lateness timer expiring, wherein the lateness timer is based on the wakeup time and the time critical task deadline.

2. The method of claim 1 , further comprising:

notifying the processing unit that the thread is in an idle state, wherein the idle state indicates that the thread is awake and ready to resume execution and execute the time critical task in accordance with the schedule.

3. The method of claim 2 ,

wherein said notifying comprises a memory write to a memory of the processing unit;

wherein the method further comprises monitoring the memory, by the processing unit, for the memory write to indicate said notifying.

4. The method of claim 2 ,

wherein said notifying comprises a timed thread execution;

wherein the timed thread execution comprises:

synchronizing, via a time monitor circuit, a clock of the processing unit with a global clock;

monitoring, by the processing unit via the time monitor circuit, the clock of the processing unit with respect to the wakeup time; and

determining that the wakeup time obtains; and

wherein the method further comprises:

resuming the execution of the thread in response to said determining that the wakeup time obtains.

5. The method of claim 1 ,

wherein the overall thread deadline is based on the difference between the thread cycle time and a system dependent suspend latency.

6. The method of claim 1 ,

wherein said suspending execution of the time critical task comprises:

suspending execution of the thread; and

returning the thread to an idle state, thereby ensuring a timely wakeup of the thread for execution of another cycle of the time critical task.

7. The method of claim 1 ,

wherein the time critical task deadline is a function of the overall thread deadline and a specified thread bandwidth, and wherein the specified thread bandwidth indicates a fraction of the thread cycle time reserved for the time critical task.

8. The method of claim 1 , wherein the thread comprises a multiplexed thread, wherein the multiplexed thread is executed on the core of the processing unit, and wherein the multiplexed thread comprises:

one or more time critical tasks; and

a best effort task.

9. A system for scheduling a time critical task, the system comprising:

a processing unit;

a device configured as a hardware assist scheduler; and

a memory coupled to the processing unit and the hardware assist scheduler;

wherein the hardware assist scheduler is configured to:

determine a schedule for the time critical task based on received timing information, wherein the time critical task executes program instructions via a thread on a core of the processing unit, wherein the time critical task is a function of the overall thread deadline and a specified thread bandwidth, and wherein said determining comprises determining a wakeup time, a thread cycle time, and an overall thread deadline; and

wherein the processing unit is configured to execute the time critical task in accordance with the schedule; and

wherein the hardware assist scheduler is further configured to suspend execution of the time critical task via assertion of a thread interrupt in response to a lateness timer expiring, wherein the lateness timer is based on the wakeup time and the time critical task deadline.

10. The system of claim 9 ,

wherein the hardware assist scheduler is further configured to notify the processing unit that the thread is in an idle state, and wherein the idle state indicates that the thread is awake and ready to resume execution and execute the time critical task in accordance with the schedule.

11. The system of claim 10 ,

wherein said notifying comprises a memory write to a memory of the processing unit; and

wherein the processing unit is further configured to monitor the memory for the memory write to indicate said notifying.

12. The system of claim 9 ,

wherein the hardware assist scheduler is further configured to provide a global clock signal; and

wherein the processing unit is further configured to:

perform a timed thread execution, wherein to perform the timed thread execution, the processing unit is configured to:

synchronize, via a time monitor circuit, a clock of the processing unit with the global clock;

monitor, via the time monitor circuit, the clock of the processing unit with respect to the wakeup time; and

determine that the wakeup time obtains; and

resume the execution of the thread in response to the wakeup time obtaining.

13. The system of claim 9 ,

wherein the overall thread deadline is based on the difference between the thread cycle time and a system dependent suspend latency.

14. The system of claim 9 ,

wherein, to suspend execution of the time critical task, the hardware assist scheduler is further configured to:

suspend execution of the thread; and

return the thread to an idle state, thereby ensuring a timely wakeup of the thread for execution of another cycle of the time critical task.

15. The system of claim 9 ,

wherein the time critical task deadline is a function of the overall thread deadline and a specified thread bandwidth, and wherein the specified thread bandwidth indicates a fraction of the thread cycle time reserved for the time critical task.

16. The system of claim 9 ,

wherein the thread comprises a multiplexed thread, wherein the multiplexed thread is executed on the core of the processing unit, wherein the multiplexed thread comprises:

one or more time critical tasks; and

a best effort task.

17. A non-transitory computer readable memory medium storing program instructions executable by at least one processor to:

determine a schedule for a time critical task based on received timing information, wherein the time critical task executes program instructions via a thread on a core of a processing unit, wherein the time critical task is a function of the overall thread deadline and a specified thread bandwidth, and wherein said determining comprises determining a wakeup time, a thread cycle time, and an overall thread deadline;

notify the processing unit that the thread is in an idle state, wherein the idle state indicates that the thread is awake and ready to resume execution and execute the time critical task in accordance with the schedule; and

suspend execution of the time critical task via assertion of a thread interrupt in response to a lateness timer expiring, wherein the lateness timer is based on the wakeup time and the time critical task deadline.

18. The non-transitory computer readable memory medium of claim 17 ,

wherein to notify the processing unit, the program instructions are further executable to perform a memory write to a memory of the processing unit.

19. The non-transitory computer readable memory medium of claim 17 ,

wherein the overall thread deadline is based on the difference between the thread cycle time and a system dependent suspend latency.

20. The non-transitory computer readable memory medium of claim 17 ,

wherein the time critical task deadline is a function of the overall thread deadline and a specified thread bandwidth, and wherein the specified thread bandwidth indicates a fraction of the thread cycle time reserved for the time critical task.

Assignments (5)
RELEASE OF SECURITY INTEREST IN PATENTS (REEL/FRAME 057280/0028) Recorded Oct 13, 2023
From: WELLS FARGO BANK, NATIONAL ASSOCIATION, AS ADMINISTRATIVE AGENT
To: NATIONAL INSTRUMENTS CORPORATION
Reel/Frame 065231/0466 →
RELEASE OF SECURITY INTEREST IN PATENTS (REEL/FRAME 052935/0001) Recorded Oct 13, 2023
From: WELLS FARGO BANK, NATIONAL ASSOCIATION, AS ADMINISTRATIVE AGENT
To: NATIONAL INSTRUMENTS CORPORATION; PHASE MATRIX, INC.
Reel/Frame 065653/0463 →
SECURITY INTEREST Recorded Jun 18, 2021
From: NATIONAL INSTRUMENTS CORPORATION
To: WELLS FARGO BANK, NATIONAL ASSOCIATION
Reel/Frame 057280/0028 →
SECURITY INTEREST Recorded Jun 14, 2020
From: NATIONAL INSTRUMENTS CORPORATION; PHASE MATRIX, INC.
To: WELLS FARGO BANK, NATIONAL ASSOCIATION
Reel/Frame 052935/0001 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Aug 28, 2015
From: CHANDHOKE, SUNDEEP; SALMON, HERBERT K., IV
To: NATIONAL INSTRUMENTS CORPORATION
Reel/Frame 036451/0726 →