Saturday, June 18, 2011

vmm_broadcast and vmm_scheduler !!!

Channels are point-to-point data transfer mechanisms. If multiple consumers had to extract same transaction descriptors from a channel then vmm_broadcast should be used. vmm_broadcast broadcasts transaction from one source channel to multiple output channels. Copy of the transaction from the source channel is forwarded to the output channels. Assume if you have multiple interfaces having different signal level protocol transmitting the same transaction at the same time a VMM broadcast can be used in this scenario. Unified generator is connected to the source channel of the vmm_broadcast and output channels of the broadcast are connected to the drivers of the interfaces.

Vmm_scheduler directs the transaction from different input channels to single output channel based on a scheduling algorithm. The default scheduling algorithm is round robin mode, by adjusting the constraint you can also have a random scheduling implemented. If you need custom scheduling you can implement the same in the vmm_scheduler_election class. Scheduler can be used if you need to schedule transactions based on some timing information.