Questions regarding Multiprocessing

[tsg 0 0 0 0 0 0 0]

Hi,
I'm a bit confused on how multiprocessing works on spresense. I've noticed the documentation mention that there are 6 "equal" application core. But the Arduino library has an example where there is one main core and the other sub cores are programmed individually. The C++ SDK also has an example which uses symmetric and asymmetric multiprocessing.

Here are my questions:
-> Can you please explain how multiprocessing can be used on spresense?
-> From what I've understood, Nuttx is not used to handle any of the multiprocessing. Is this correct?
-> Can you please share which library should be used for multiprocessing and the examples for them?

Thanks

[KamilTomaszewski]

Hi @tsg-0-0-0-0-0-0-0 ,

You can use ASMP or SMP. You can also use them together.

Information about ASMP can be found here: https://developer.sony.com/develop/spresense/docs/sdk_developer_guide_en.html#_asmp_framework. This is a framework that provides initialization and communication between cores. ASMP does not use NuttX. Example: https://github.com/sonydevworld/spresense/tree/master/examples/asmp/

Information about SMP you can find here: https://developer.sony.com/develop/spresense/docs/sdk_tutorials_en.html#_feature_smp and https://nuttx.apache.org/docs/latest/reference/os/smp.html. SMP is controlled by NuttX so you just have to enable it and assign how many cores you want to allocate for SMP. Example: https://github.com/sonydevworld/spresense-nuttx-apps/tree/1a501330f462e8d433c31fd6f6b7822a70ed0c26/testing/smp

You can use ASMP and SMP together. You can see how this works using example/smp_asmp config.

Best Regards,
Kamil Tomaszewski