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L3 interconnect predictability

Richard van Berkel
Prodigy 215 points

Dear TI employees,

For a project I have to implement a piece of periodic fired software on the OMAP4460 MPSoC (Pandaboard ES) in such a way that hard real-time guarantees can be given. The piece of software will be running in parrallel with other hard and soft real-time applications and hence I need to come up with some reservation-based resource management strategy. In order to do so I need at least more information on the Arteris L3 interconnect which I was not able to find in both the TRM and on the internet. Questions regarding the interconnect are given below:

I have the following questions regarding the Arteris L3 interconnect:
* Which topology is used? E.g. a mesh network?
* Which arbitration algorithm is used? E.g. Round robin (RR) or first-come-first-serve (FCFS)?
* Which routing algorithm is used?
* How predictable are the transmission times? In other words, for each master network interface unit (master NIU) I want to be able to predict (bound) how much time it takes (minimum and maximum) to transfer a certain amount of data to a given slave NIU.
* In what extend do the different data flows influence each other? E.g. I would like to know in what extend the traffic from the A9 MPU subsystem to the L4_PER interconnect influences the traffic form the M3 MPU subsystem to the L4_PER interconnect.
* Which mechanisms from the Arteris L3 interconnect can be used in order to make certain connections between master NIUs and slave NIUs over the interconnect more predictable? E.g. is it possible to assign priorities?  

Thanks in advance.

Kind regards,

Richard van Berkel.

  • 0
    Prodigy 215 points

    I noticed I forgot to mention the following:
    I do this project for graduation purpose only (MSc Embedded Systems), pure scientific research within the real-time systems field.  

  • 0 in reply to Richard van Berkel
    TI__Guru**** 161600 points

    Hello Richard,

    Unfortunately I can answer very little of your questions, because as you've noticed L3 NOC is a third party IP  provided by Arteris, and most of the information you require is confidential. You need to have NDA agreement to acquire it.

    What I can answe is:


    Which topology is used? E.g. a mesh network?

    The paths between the masters and slaves in the L3 interconnect are hardwired, you can see which master can access which slave from the Connectivity Matrix shown in the TRM. When you make the connections described there the closest thing that comes is a Mesh Network.

    Which arbitration algorithm is used? E.g. Round robin (RR) or first-come-first-serve (FCFS)?

    It uses round robin arbitration.

    In what extend do the different data flows influence each other? E.g. I would like to know in what extend the traffic from the A9 MPU subsystem to the L4_PER interconnect influences the traffic form the M3 MPU subsystem to the L4_PER interconnect.

    To my knowledge such tests were not performed by TI.In the example you've given the masters are connected to different ports of the L4_PER Interconnect.

    is it possible to assign priorities

    Yes, to very little extend you can assign priorities to some modules traffic: see Bandwidth Regulators section. Also some modules for example ISS have internal means to assign priority to their packages.

    This is the information I can share with you in the public forum.

    Hope it is helpful.

    Best Regards,

    Yordan

  • 0 in reply to Yordan Kovachev
    Prodigy 215 points

    Dear Yordan,

    Thanks a lot for your reply! I appreciate it. It is a good start. 

    Maybe you can give me some additional advice on how to proceed? E.g. you might have an idea who I should contact in order to collect more information (possibly under NDA since the results of my research might also be interesting for TI)?

    Kind regards,

    Richard.

  • 0 in reply to Richard van Berkel
    TI__Guru**** 161600 points

    You should contact the customer support centers:

    For North, South and Central America: http://www.ti.com/ww/en/csc/support-Americas.html

    For Asia: http://www.ti.com/ww/en/csc/support-Asia.html

    For Europe, Middle East and Africa: http://www.ti.com/ww/en/csc/support-EMEA.html

    For Japan: http://www.ti.com/ww/en/csc/support-Japan.html

    Details on how to contact them (phone & email addresses) are shown in the links.

    Best Regards,

    Yordan