What is the maximum transmission interprocessor bandwidth on STM32MP1?

[robsen223]

I am interested in the maximum transmission bandwidth between the A7 core and M4 core on the STM32MP1.

I did some test using RPMsg framewirk and sent messages with length 496 Byte from the A7 core to the M4 core. Therefore I modified the OpenAMP_raw example. I measured the time which it takes to receive 2300 messages on the M4 side using HAL_getTick(). I measured an average time of 132 ms, which would result in a transmission bandwidth of just 8,64 MB/s, which seems pretty slow to me.

Has anyone made some experience with it or did some similar evaluation? Maybe me measurement method isnt optimal? I am thankful for evey opinion.

[Olivier GALLIEN · Accepted solution]

Hi @robsen223​ 

Could you please confirm data you provided ?

Computing given data we found 8,6MB/s ( 2300*496/0.132)

For your information, in an dedicated optimized environment we achieved 15.4MB/s (512 Bytes buffer size).

But this is really dependent of context on both cores and application.

Else generally speaking bandwidth can be enhanced :

• by increasing RPMSG Buffer size, but till a reasonable limit (eg 2048) since RPMSG is designed for message (control ) and not data.
• by using a shared memory ( rpmsg used for pointers exchange between cores)

BR,

Olivier

[robsen223]

Hi @Community member​ 

you are absolutely right with 8,6MB/s. I mixed up my notes.

Thank you for your comments. It gave my the right food of thought and helped me to finish my work. Especially I thought that RPMsg is the only option for data transmisson. I really like the idea of sending just pointer through RPMsg.

[USama1]

Hi robsen223,

I am trying to write similar user application on linux for Inter core communication, could you clarify on how to write text via rpmsg on linux.

Thank you

[Olivier GALLIEN]

Hi @USama​ 

I suggest you to have a look to sample application "OpenAMP_TTY_Echo" installed on Starter Package and source available in STM32MP1 Cube Package.

https://wiki.st.com/stm32mpu/wiki/STM32CubeMP1_Package#Getting_started_with_STM32CubeMP1_Package

Hope it help,

Olivier

[lenonrt]

Hi @Community member​ !

I'm trying to understand how to use a shared memory.

Can you help me?

I think that the shared memory I should use is this:

sram: sram@10050000 {
		compatible = "mmio-sram";
		reg = <0x10050000 0x10000>;
		#address-cells = <1>;
		#size-cells = <1>;
		ranges = <0 0x10050000 0x10000>;
 
		dma_pool: dma_pool@0 {
			reg = <0x0 0x10000>;
			pool;
		};
	};

How can I access it? There is a specific driver (misc/sram)?

Thank you!

Lenon