LOCK CONTROL IN MULTIPLE PROCESSOR SYSTEMS

• US 20130305253A1
• Filed: 03/07/2013
• Published: 11/14/2013
• Est. Priority Date: 05/19/2011
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Allen, Gerald Martyn Worsfold
• Granted Patent: US 8,850,441 B2
• Time in Patent Office: Days
• US Class Current: 718/103
• CPC Class Codes: G06F 2209/483 Multiproc
• CPC Class Codes: G06F 2209/485 Resource constraint
• CPC Class Codes: G06F 9/4881 Scheduling strategies for dispatcher, e.g. round robin, multi-level priority queues
• CPC Class Codes: G06F 9/526 Mutual exclusion algorithms

Abstract

A computer implemented method executing a plurality of tasks, each task comprising threads and each task being assigned a priority from 1 to a whole number greater than 1, each thread of a task assigned the same priority as the task and each thread being executed by a processor. The method also provides locking and unlocking arranged to lock and unlock data stored by a storage device responsive to such a request from a thread. A method of operating the system comprises maintaining a queue of threads that require access to locked data, maintaining an array comprising, for each priority, duration and/or throughput information for threads of the priority, setting a wait flag for a priority in the array according to a predefined algorithm calculated from the duration and/or throughput information in the array.

Claims

1. A method of operating a system comprising a plurality of processors and one or more storage devices, the system arranged to execute a plurality of tasks, each task comprising one or more threads and each task being assigned a priority from 1 to a whole number greater than 1, each thread of a task being assigned a same priority as a corresponding task and each thread being executed by a processor of the system, the system providing lock and unlock functions arranged to lock and unlock data stored by a storage device in response to a request from a requesting thread, the method comprising:

maintaining a queue of threads that require access to locked data;

maintaining an array comprising, for each priority, at least one of a duration and a throughput information for threads of the priority;

setting a wait flag for the priority in the array according to a predefined algorithm calculated from the at least one of the duration and the throughput information in the array;

responsive to a thread releasing a lock on data, determining that the next thread that requires a lock on the released data is to be executed on a processor for the thread that released the lock;

responsive to determining that the next thread that requires the lock on the released data is to be executed on the processor for the thread that released the lock, determining that the wait flag is set in the array for a priority of a next thread; and

responsive to a determination that the wait flag is set in the array for a priority of a next thread, delaying execution of the next thread for a predetermined time delay.

2. The method of claim 1 further comprising:

following the delay of the execution of the next thread for the predetermined time delay, deleting the wait flag for the priority of the next thread in the array.

3. The method of claim 1, wherein setting the wait flag for the priority in the array according to the predefined algorithm calculated from the at least one of the duration and throughput information in the array comprises detecting, compared to an array element of a set priority and a corresponding throughput, an array element of a lower priority and a higher throughput, wherein the array element of the set priority and the corresponding throughput and the array element of the lower priority and higher throughput are members of the array.

4. The method of claim 1, wherein setting the wait flag for the priority in the array according to the predefined algorithm calculated from the at least one of the duration and throughput information in the array comprises detecting, compared to an array element of a set priority and a corresponding duration, an array element of a lower priority and a shorter duration, wherein the array element of the set priority and the corresponding throughput and the array element of the lower priority and shorter duration are members of the array.

5. The method of claim 1 further comprising:

completing a thread of the one or more threads to form a completed thread, and responsive to completing, updating the array for a priority of the completed thread with a duration and a throughput for the completed thread.

6. The method of claim 5 comprising:

responsive to updating the array for the priority of the completed thread with the duration and the throughput for the completed thread, applying smoothing to the updating according to a defined formula.