Method and apparatus for synchronization of periodic processes

• US 7,712,099 B2
• Filed: 11/02/2004
• Issued: 05/04/2010
• Est. Priority Date: 02/16/2001
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Shell, Scott R., Vargas, Garrett R., Taylor, Matthew W.
• Primary Examiner(s): Bullock, Jr.; Lewis A
• Assistant Examiner(s): WANG, JUE S
• Application Number:
  US10/978,481
• Publication Number:
  US 20050132372A1
• Time in Patent Office: 2,009 Days
• Field of Search: 718100-108
• US Class Current: 718/102
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/329 by task scheduling
• CPC Class Codes: G06F 11/0715 in a system implementing multitasking multitasking per se G06F9/46
• CPC Class Codes: G06F 11/0757 by exceeding a time limit, i.e. time-out, e.g. watchdogs
• CPC Class Codes: G06F 11/0793 Remedial or corrective actions recovery from an exception in an instruction pipeline G06F9/3861; by retry G06F11/1402; for recovering from a failure of a protocol instance or entity H04L69/40
• CPC Class Codes: G06F 9/4825 Interrupt from clock, e.g. time of day
• CPC Class Codes: G06F 9/4881 Scheduling strategies for dispatcher, e.g. round robin, multi-level priority queues
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A system and method is disclosed for synchronizing certain periodic activities and/or processes in a computer system or device. The synchronization allows more efficient use of the computer system'"'"'s or device'"'"'s processing capabilities, and may result in conservation of electrical power. In one example embodiment, a periodic scheduler is implemented to periodically verify the continued existence of critical processes operating in the computer system or device. Corrective, or other appropriate, action may be taken in the event of a failure of a critical process. A schedule list, which may be a linked list, may be used to track the periodic processes that are to occur. Upon registration of a critical process, the schedule list may be modified to synchronize the new periodic process with the existing schedule list.

Claims

1. A computer-readable storage medium which stores a set of computer-readable instructions which when executed perform a method for periodic process synchronization, the method executed by the set of computer-readable instructions comprising:

storing, in a memory, a schedule list comprising a plurality of time entries indicating a maximum amount of times at which a plurality of critical processes are to be checked and a minimum amount of times at which the plurality of critical processes are to be checked to determine whether said plurality of critical processes remain active, wherein the schedule list comprises a last time entry in said schedule list including a time value that is a common multiple of a plurality of periods associated with said plurality of critical processes, and wherein the plurality of critical processes specify the plurality of time entries including wildcard values for time entry registry into the schedule list;

registering at least one new critical process to be checked;

synchronizing the at least one new critical process with the schedule list, wherein synchronizing the at least one new critical process comprises;

determining whether a period associated with the at least one new critical process comprises a multiple of the time value of the last time entry of the schedule list, and

in response to determining that a period associated with the at least one new critical process does not comprise a multiple of the time value of the last time entry of the schedule list, extending the schedule list to a new last time entry comprising a new time value that is a common multiple of the plurality of periods associated with said plurality of critical processes and the period associated with the at least one new critical process;

when the maximum amount of times at which a first one of the plurality of critical processes is to be checked and the minimum amount of times at which the first one of the plurality of critical processes is to be checked do not comprise a wildcard value, using said schedule list to periodically verify that said first one of the plurality of critical processes remains active within the maximum and the minimum amount of times indicated by the plurality of time entries;

when both the maximum amount of times at which a second one of the plurality of critical processes is to be checked and the minimum amount of times at which the second one of the plurality of critical processes is to be checked comprise the wildcard value, the wildcard value being expressed as a zero time value and indicating an open end of a time range, using said schedule list to periodically verify that said second one of the plurality of critical processes remains active during a periodic verification of each of the plurality of critical processes; and

taking corrective action when at least one of said plurality of critical processes no longer remains active.

2. The computer-readable storage medium of claim 1, further comprising:

sending a first signal to a first critical process at a first time in said schedule list;

waiting for a second time in said schedule list, wherein said second time corresponds to said first critical process;

at said second time, determining whether a response to said first signal was received from said first critical process;

resending said first signal to said first critical process if said response was received; and

taking corrective action if said response was not received from said first critical process.

3. The computer-readable storage medium of claim 2, wherein taking corrective action if said response was not received from said first critical process comprises taking corrective action by restarting said first critical process.

4. The computer-readable storage medium of claim 1, wherein said schedule list further comprises information identifying at least one of said plurality of critical processes.

5. The computer-readable storage medium of claim 1, wherein said computer-readable storage medium is enclosed within a portable computing device.

6. The computer-readable storage medium of claim 5, wherein said portable computing device is one of a cellular telephone and a pager.

7. The computer readable storage medium of claim 1, wherein a wildcard time entry in the schedule list adjusts the plurality of critical processes'"'"' periodic event frequency.

8. A computing device for periodic process synchronization, the computing device comprising:

a memory storage; and

a processing unit coupled to the memory storage, wherein the processing unit is operative to;

provide a schedule list having entries of time information and event identification information associated with a plurality of processes, wherein the schedule list comprises a plurality of time entries indicating a maximum amount of times at which said plurality of processes are to be checked and a minimum amount of times at which said plurality of processes are to be checked to determine whether said plurality of processes remain active, and wherein the schedule list comprises a last time entry in the schedule list including a time value that is a common multiple of a plurality of periods associated with said plurality of processes, the plurality of processes being operative to specify a plurality of time entries including wildcard values for time entry registry into the schedule list;

register at least one new process;

synchronize the at least one new process with said schedule list, wherein being operative to synchronize the at least one new process comprises being operative to;

determine whether a period associated with the at least one new process comprises a multiple of the time value of the last time entry of the schedule list, and

in response to determining that a period associated with the at least one new process does not comprise a multiple of the time value of the last time entry of the schedule list, extending the schedule list to a new last time entry comprising a new time value that is a common multiple of the plurality of periods associated with said plurality of processes and the period associated with the at least one new process;

when the maximum amount of times at which a first one of the plurality of processes is to be checked and the minimum amount of times at which the first one of the plurality of processes is to be checked do not comprise a wildcard value, use said schedule list to periodically verify that said first one of the plurality of processes remains active within the maximum and the minimum amount of times indicated by the plurality of time entries;

when both the maximum amount of times at which a second one of the plurality of processes is to be checked and the minimum amount of times at which the second one of the plurality of processes is to be checked comprise the wildcard value, the wildcard value being expressed as a zero time value and indicating an open end of a time range, use said schedule list to periodically verify that said second one of the plurality of processes remains active during a periodic verification of each of the plurality of processes; and

take corrective action when at least one of said plurality of processes no longer remains active.

9. The device of claim 8, wherein a first one of said processes is a critical process monitor, and at least one of said plurality of processes includes a critical process.

10. The device of claim 8, wherein said memory storage comprises a single memory storage unit.

11. The device of claim 8, wherein said processing unit is a single processor.

12. The device of claim 8, wherein the schedule list includes a wildcard time entry which adjusts the plurality of processes'"'"' periodic event frequency.

13. A computer-readable storage medium which stores a set of computer-readable instructions which when executed perform a method for periodic process synchronization, the method executed by the set of computer-readable instructions comprising:

storing, in a memory, a schedule list having a plurality of time entries indicating a maximum amount of times at which a plurality of critical processes are to be checked, a minimum amount of times at which the plurality of critical processes are to be checked to determine whether the plurality of critical processes remain active, and a last time entry including a time value that is a common multiple of a plurality of periods associated with said plurality of time entries, and wherein the plurality of critical processes specify the plurality of time entries including wildcard values for time entry registry into the schedule list;

registering at least one new critical process to be checked;

synchronizing the at least one new critical process with the schedule list, wherein synchronizing the at least one new critical process comprises;

determining whether a period associated with the at least one new critical process comprises a multiple of the time value of the last time entry of the schedule list, and

in response to determining that a period associated with the at least one new critical process does not comprise a multiple of the time value of the last time entry of the schedule list, extending the schedule list to a new last time entry comprising a new time value that is a common multiple of the plurality of periods associated with said plurality of critical processes and the period associated with the at least one new critical process;

when both the maximum amount of times at which a first one of the plurality of critical processes is to be checked and the minimum amount of times at which the first one of the plurality of critical processes is to be checked comprise the wildcard value, expressed as a zero time value and indicating an open end of a time range, using said schedule list to periodically verify that said first one of the plurality of critical processes remains active during a periodic verification of each of the plurality of critical processes; and

when the maximum amount of times at which a second one of the plurality of critical processes is to be checked and the minimum amount of times at which the second one of the plurality of critical processes is to be checked do not comprise a wildcard value, using said schedule list to periodically verify that said second one of the plurality of critical processes remains active, wherein using the schedule further comprises;

sending a first signal to a first critical process at a first time in the schedule list,

waiting for a second time in the schedule list, wherein the second time corresponds to the first critical process,

at the second time, determining whether a response to the first signal was received from the first critical process,

resending the first signal to the first critical process if the response was received, and

taking corrective action if the response was not received from the first critical process.