公开(公告)号：US10310891B2

公开(公告)日：2019-06-04

申请号：US14871837

申请日：2015-09-30

Applicant: Apple Inc.

Inventor： Daniel A. Chimene ,  Daniel A. Steffen ,  James M Magee ,  Russell A. Blaine ,  Shantonu Sen

IPC: G06F9/48 ,  G06F9/50 ,  G06F9/46

Abstract: Disclosed herein are systems, methods, and computer-readable media directed to scheduling threads in a multi-processing environment that can resolve a priority inversion. Each thread has a scheduling state and a context. A scheduling state can include attributes such as a processing priority, classification (background, fixed priority, real-time), a quantum, scheduler decay, and a list of threads that may be waiting on the thread to make progress. A thread context can include registers, stack, other variables, and one or more mutex flags. A first thread can hold a resource with a mutex, the first thread having a low priority. A second thread having a scheduling state with a high priority can be waiting on the resource and may be blocked behind the mutex held by the first process. A scheduler can execute the context of the lower priority thread using the scheduler state of the second, higher priority thread. More than one thread can be waiting on the resource held by the first thread. A “pusher list” of threads that are waiting on the first thread can be associated with the first thread. The scheduler can use the pusher list to identify threads that need the first thread to make progress until the first thread releases the resource and mutex. Then, the scheduler can use the pusher list to identify threads that are now runnable and make immediate use of the resource.