FreeRTOS port

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akp
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Re: FreeRTOS port

Postby akp » Tue Nov 05, 2019 5:05 pm

Changing the kernel assembly to dual issue on the XS2A seems to reduce the context switch time by roughly 15%.
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akp
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Postby akp » Thu Dec 12, 2019 9:20 pm

Not surprisingly, rewriting the kernel assembly in dual-issue yields an improvement
fabriceo
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Postby fabriceo » Tue Dec 31, 2019 9:26 am

Hi see this RTOS stack implementation for freertos for VocalFusion. ver active GitHub branch
https://github.com/xmos/lib_rtos_support
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akp
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Postby akp » Tue Dec 31, 2019 12:27 pm

Thanks, I will take a look.
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Postby akp » Tue Dec 31, 2019 7:04 pm

I took a look at the FreeRTOS port and I wonder if it supports dual-issue mode? It doesn't look like it would work if the FreeRTOS core were running dual-issue code, it might generate exception when it returns from kcall. With respect the kernel assembly I wrote is faster (takes advantage of dual-issue features to perform context switch quicker) and it supports context switching a FreeRTOS core running dual-issue code. The examples are compiled -Os so that means they're tested in single-issue mode.

EDIT: Obviously the big advantage of the XMOS FreeRTOS port is that it supports SMP whereas I can run only one FreeRTOS core per tile. So I am not pooh-poohing it. I just don't have a need for SMP FreeRTOS at present so optimizing the single core FreeRTOS for speed seemed to be a better option for me, leaving more MIPS and cores for xc tasks which is where most of my stuff gets done (e.g. time critical stuff or co-operative multitasking using combinable tasks).

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