Re: [cip-dev] preempt_rt on BeagleV-Fire

[Pavel Machek <pavel@nabladev.com>]

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Hi!

> has anyone already tested preempt_rt on the BeagleV-Fire?
> 
> OSADL has evaluated preempt_rt on both the PolarFire Icicle Kit
> (MPFS250T) and the PolarFire Discovery Kit (MPFS095T) and has reported
> rather problematic latency results so far[1].
> 
> Since the BeagleV-Fire is also based on a PolarFire SoC (MPFS025T), I
> suspect we might run into similar issues. Any experiences, measurements,
> or insights would be greatly appreciated.

Those OSADL results actually look good to me :-).

Ok, so let me explain. BeagleV-Fire seems to have slow CPUs. Like
"Nokia N900" slow. That's TI OMAP 3430 SoC, 600 MHz ARM Cortex-A8 CPU
from 2010 or so.

It is certainly less than 10% of speed of Core i9-9900K, and that one
reaches 100usec...

https://www.osadl.org/Latency-plot-of-system-in-rack-0-slot.qa-latencyplot-r0s5.0.html?latencies=&showno=&shadow=1&slider=360

...so 350usec is actually not that bad, AFAICT.

Not sure what our requirements are, sometimes people put the
time-critical stuff into FPGA.

Best regards,
								Pavel
-- 
In cooperation with Nabla.

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