arbitration delay/penalty

[Mandy]

Hi,

Is there any penalty incurred on VC and/or SW arbitration in TOPAZ ? It seems the arbitration policy is FCFS, in which case there won't be any  penalty. Could please validate this?

Thanks,
Monobrata

[Pablo Abad]

The penalty of VC/SW arbitration depends on the components employed to build the router. SimpleRouters normally consider a 1-cycle penalty for each stage, The length of Switch Arbitration can be controlled through HeaderDelay variable. (see code of TPZSimpleRouter).

In the case of WH routers the length of these two stages can be modified through vcarbDelay and swarbDelay variables (see Router.sgm -> WH-BASE router for details).

Arbitration policy at simpleRouters is Round Robin, not FCFS. Alternatives to this one have not been implemented (could be easily done). 

--
You received this message because you are subscribed to the Google Groups "topaz-discuss" group.
To unsubscribe from this group and stop receiving emails from it, send an email to topaz-discus...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[Monobrata Debnath]

I am talking about arbitration policy in complex router. E.g in TPZCrossbardFlowVC.cpp .Check the following links:

https://code.google.com/p/tpzsimul/source/browse/src/TPZCrossbarFlowVC.cpp#181 for (VC Arbitration)

and

https://code.google.com/p/tpzsimul/source/browse/src/TPZCrossbarFlowVC.cpp#239 (SW Arbitration)

Are they Round-Robin or FCFS?

--
You received this message because you are subscribed to a topic in the Google Groups "topaz-discuss" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/topaz-discuss/7AfhpZTn_3M/unsubscribe.
To unsubscribe from this group and all its topics, send an email to topaz-discus...@googlegroups.com.

[Pablo Abad]

In the Event queue messages are ordered according to the value passed as second argument to the enqueue function (see next lines to the ones you indicate in your question).  In that particular case, where delayTime=current cycle and if the VCArbitrationDelay is a fixed value, yes, both arbitrations are FCFS.