All DMA commands except getllar, putllc, and putlluc can be tagged with a 5-bit Tag Group ID.
By assigning a DMA command or group of commands to different tag groups, the status of the entire tag group can be determined within a single command queue (the MFC SPU Command Queue or the MFC Proxy Command Queue).
Software can use this identifier to check or wait on the completion of all queued commands in one or more tag groups. Tagging is optional but can be useful when using barriers to control the ordering of MFC commands within a single command queue.
DMA commands within a tag group can be synchronized with a fence or barrier option by appending an f or b, respectively, to the command mnemonic. Execution of a fenced command option is delayed until all previously issued commands within the same tag group have been performed. Execution of a barrier command option and all subsequent commands is delayed until all previously issued commands in the same tag group have been performed.