Shared resources in a data processing appartus for executing a plurality of threads

Abstract

A data processing apparatus (100) executes threads and includes a general program counter (PC) (120) identifying an instruction to be executed for at least a subset of the threads. Each thread has a thread PC (184). The subset of threads has at least one lock parameter (188, 500-504) for tracking exclusive access to shared resources. In response to a first instruction executed for a thread, the processor (160) modifies the at least one lock parameter (188), (500-504) to indicate that the thread has gained exclusive access to the shared resource. In response to a second instruction, the processor modifies the at least one lock parameter (188, 500-504) to indicate that the thread no longer has exclusive access. A selector (110) selects one of the subset of threads based on the at least one lock parameter (188, 500-504) and sets the general PC (120) to the thread PC (184) of the selected thread.

Description

technical field [0001] This technology relates to the field of digital processing. In particular, the technology studies data processing devices and methods in which multiple threads are executed. Background technique [0002] A data processing device may execute multiple threads. Threads can progress in lockstep. Specifically, each thread may maintain its own program counter. The system itself may maintain its own general-purpose program counter, such that the instruction indicated by the general-purpose program counter is executed for the thread (for which the program counter matches the general-purpose program counter). Such systems may be referred to, for example, as Single Instruction Multiple Thread (SIMT) systems. Thus, at each step, a single instruction is executed for at least a subset of the plurality of threads. Once an instruction has been executed for a subset of threads, the general program counter can be changed to indicate the new instruction. In such s...

AI Technical Summary

Problems solved by technology

Therefore, the rest of the threads will be able to execute, but the threads that have access to the shared resource will not be able to execute

Deadlock occurs because other threads will not be able to access the shared resource while another thread has access to the shared resource

However, a thread with access to a shared resource may never be allowed to execute

Therefore, no thread makes any progress and the system halts

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