On 2 November 2015 at 07:52, William Hermans <yyrk...@gmail.com> wrote:
> Determinism. I do agree with what you're saying, but sometimes, you need > things to happen at exactly <some time interval >. In userland, you may be > able to achieve that most of the time, but you will not be able to achieve > that all of the time. Even if that time interval does not happen very often. > Determinism is relative. RT kernels should in principle allow things to happen within <some time interval> all of the time, provided the interval is not too tight, you correctly configured priorities, and you don't run into a seriously misbehaving driver. PRUSS of course offers absolute determinism, but only if you stay within the subsystem. As soon as you start using peripherals outside it your timing starts getting affected by interconnect traffic from the cortex-A8. For some applications even the jitter due to competing interconnect traffic is already bad. For most however the jitter of an RT kernel is probably fine. As an added bonus, we get to offload the main core in the process :) > I'd consider PRU to be a more precious resource than cortex-A8 cycles though. > So /dev/iio:device0 is a buffer for the ADC when operating in continuous > mode > Ah, yes I also use a tiny ring buffer for ADC which I reserved (using DT) in OCMC ram. Configured DMA to write the ADC data to the buffer whenever it's available, and userspace can simply read the latest measurements from the buffer whenever it needs them. > I now consider iio a waste of time. In a way, like you, I do not like > unnecessary abstraction layers. Especially those that seem to fight against > ones willingness to learn > I have to admit I didn't look at it very long, but to me it also seemed overly complicated and opaque. Anyhow, I noticed we've drifted slightly off-topic here... ;-) -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
