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Speed of SC145 versus SC24

Questions and discussions about the operating system RTOS and the corresponding C-LIB.

Speed of SC145 versus SC24

Postby Aldo Om. » 24.01.2019, 11:14

I use SC24 from long time and I am happy with its performance. Now I should evaluate a new application in C language where I need to perform fast operations on the GPIO and also perform a large amount of code in a task of few ms (eg 5ms).
From tests performed on both SC24 and SC145 I noticed that the set and reset of the GPIOs requires some us (5-10us and more). The SC145 also seems slower to handle GPIOs.
Do you have any information on the performance in terms of speed of both the GPIOs and the execution of the C code in general for both processors ?
Do you think that SC145 (RISC) is much faster of the SC24 (CISC) for the processing of the same C program?

Thank you.

Hello Aldo,

The SC145 also seems slower to handle GPIOs.


We have improved the GPIO handling performance compared to old versions of the RTOS-LNX OS. Which version are you testing with?

Do you have any information on the performance in terms of speed of both the GPIOs and the execution of the C code in general for both processors ?


We did conduct tests but the results are not available to me right now. If you are sure that you are using the latest RTOS-LNX version and you still measure the SC145 to be slower, I will definitely look into the matter again.

Do you think that SC145 (RISC) is much faster of the SC24 (CISC) for the processing of the same C program?


Definitely yes.

Regards
Michael G. Etairidis
Software Development
Beck IPC GmbH

Re: Speed of SC145 versus SC24

Postby Aldo Om. » 26.01.2019, 16:27

my current RTOS version is 122 and it seems that it is the most recent available on the site.

Thanks for the info

Yes, you are right, V1.22 is the latest version. I will look into this and get back to you. One more quick question: which function are you using to set the output state gpioWriteOutput() or gpioWriteBankOutputs()?
Michael G. Etairidis
Software Development
Beck IPC GmbH

I can confirm that switching GPIOs on the SC145 takes around 10us. I got confused with another target when I said that it should be faster than the SC24. The reason for this is that setting the GPIO registers for the SC145 is not an atomic action and it, therefore, needs to be protected at the kernel level and this causes a lot of overhead.

We are actively trying to improve this and I will get back to you if we find a faster way to do this.
Michael G. Etairidis
Software Development
Beck IPC GmbH

Re: Speed of SC145 versus SC24

Postby Aldo Om. » 01.02.2019, 17:40

I'm sorry for my slow reaction to the Forum but I had not set up the email notification of an answer.

Unfortunately complex systems allow things that simpler processors do not allow but often do not have the same speed for peripheral management, required in many control applications. My small 8-bit Silicon Lab processors run x 180 faster. I will have to find a way to combine these two different devices on the same card, at least until you find a way to access I/O faster.

Thanks for the answers.

I agree.

We really like the countless benefits of using a powerful OS like Linux under the hood but with the good comes the bad. We were also kind of surprised with the register architecture of the processor when we first found out that setting a GPIO is not an atomic action (and kind of got the feeling that silicon designers have stopped thinking about us "fast and efficient" embedded developers) but it is what it is. We are currently looking for a way around it. We either will find a faster way to protect this action or provide an additional API for users that know that they are not accessing the same GPIO registers from multiple threads so that no protection is necessary. With no multi-thread protection, setting the GPIOs should take around 30ns.

Regards
Michael G. Etairidis
Software Development
Beck IPC GmbH

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