Out-of-order command execution with sliding windows to maintain completion statuses

An apparatus comprising:

• a command distribution and synchronization processor,
• wherein the command distribution and synchronization processor is configured to:
• receive at least one command stream comprising first, second, and third commands, and inter-command dependency information;
• receive the inter-command dependency information in the at least one command stream before execution of the first, second, and third commands, wherein the first, second, and third commands in the at least one command stream are in addition to the inter-command dependency information in the at least one command stream, wherein the inter-command dependency information comprises a dependency list for the second command, wherein the dependency list for the second command references, via command count values, any commands in the at least one command stream upon which the second command depends, wherein each command count value represents a respective previous command in the at least one command stream, wherein the second and third commands have a first order in the at least one command stream such that the second command precedes the third command;
• determine, based on the dependency list for the second command, that the second command depends upon prior execution of the first command;
• determine that the first command is associated with a first one of a plurality of processing pipelines and that the second command and third commands are associated with a second, different one of the plurality of processing pipelines;
• distribute the third command to the second one of the plurality of processing pipelines based on determining that the second command depends upon prior execution of the first command;
• after distributing the third command to the second one of the plurality of processing pipelines, distribute, based on determining that the second command depends upon prior execution of the first command, the second command to the second one of the plurality of processing pipelines such that the second command and third command execute in a second order that is different than the first order;
• maintain a first sliding window to represent completion statuses of commands associated with the first one of the plurality of processing pipelines;
• and
• maintain a second sliding window to represent completion statuses of commands associated with the second one of the plurality of processing pipelines,
• wherein the at least one command stream comprises a first set of ordered commands associated with the first one of the plurality of processing pipelines and a second set of ordered commands associated with the second one of the plurality of processing pipelines, and
• wherein the first sliding window comprises a command counter that represents a start location of the first sliding window, wherein the start location corresponds to a last command in the first set of ordered commands for which no preceding command remains unexecuted by the first one of the plurality of processing pipelines.

A non-transitory computer-readable storage medium comprising instructions that, when executed, cause a programmable processor to:

• receive at least one command stream comprising first, second, and third commands, and inter-command dependency information;
• receive the inter-command dependency information in the at least one command stream before execution of the first, second, and third commands, wherein the first, second, and third commands in the at least one command stream are in addition to the inter-command dependency information in the at least one command stream, wherein the inter-command dependency information comprises a dependency list for the second command, wherein the dependency list for the second command references, via command count values, any commands in the at least one command stream upon which the second command depends, wherein each command count value represents a respective previous command in the at least one command stream, wherein the second and third commands have a first order in the at least one command stream such that the second command precedes the third command;
• determine, based on the dependency list for the second command, that the second command depends upon prior execution of the first command;
• determine that the first command is associated with a first one of a plurality of processing pipelines and that the second command and third commands are associated with a second, different one of the plurality of processing pipelines;
• distribute the third command to the second one of the plurality of processing pipelines based on determining that the second command depends upon prior execution of the first command;
• after distributing the third command to the second one of the plurality of processing pipelines, distribute, based on determining that the second command depends upon prior execution of the first command, the second command to the second one of the plurality of processing pipelines such that the second command and third command execute in a second order that is different than the first order;
• maintain a first sliding window to represent completion statuses of commands associated with the first one of the plurality of processing pipelines;
• and
• maintain a second sliding window to represent completion statuses of commands associated with the second one of the plurality of processing pipelines,
• wherein the at least one command stream comprises a first set of ordered commands associated with the first one of the plurality of processing pipelines and a second set of ordered commands associated with the second one of the plurality of processing pipelines, and
• wherein the first sliding window comprises a command counter that represents a start location of the first sliding window, wherein the start location corresponds to a last command in the first set of ordered commands for which no preceding command remains unexecuted by the first one of the plurality of processing pipelines.