International Business Machines Corporation

Brian D Watt

Joaquin Madruga

Gregory Howard Bellows

Ross A Mikosh

Benjamin Gale Alexander

Provided are techniques for the managing of command queue dependencies and command queue synchronization. Incoming commands are actively tracked through their dependency relationships. Command dependencies may be tracked across multiple lists, including a submission list and a completion list. Each command on the submission list is prepared for processing and ultimately submitted to command processing logic. Command completion processing is performed on each command on the completion list, including by not limited to removing dependencies from pending commands and possibly queuing pending commands for submission to the command processing logic. Also provided as features of a command queue are a standby barrier, an active barrier and a marker. Standby and active barriers are employed to synchronize and track commands through the command queue. Markers are employed to track commands through the command queue.

Synchronizing commands and dependencies in an asynchronous command queue

Execution units process commands from one or more command queues. Once a command is available on the queue, each unit participating in the execution of the command atomically decrements the command's work groups remaining counter by the work group reservation size and processes a corresponding number of work groups within a work group range. Once all work groups within a range are processed, an execution unit increments a work group processed counter. The unit that increments the work group processed counter to the value stored in a work groups to be executed counter signals completion of the command. Each execution unit that access a command also marks a work group seen counter. Once the work groups processed counter equals the work groups to be executed counter and the work group seen counter equals the number of execution units, the command may be removed or overwritten on the command queue.

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Round Rock, TX, United States of America

Brian D Watt