IR decoding with BPF

Posted Jul 13, 2018 0:52 UTC (Fri) by k8to (guest, #15413)
In reply to: IR decoding with BPF by seanyoung
Parent article: IR decoding with BPF

This implies that it's more efficient to have it in-kernel, but does't really explain that doing it in userspace is a performance concern for low-bandwidth links such as the one this is designed for.

In other words if doing it in user space costs 0.00000000001% of a core and doing it in kernel costs 0.000000000001%, then it's not really a performance concern.

IR decoding with BPF

Posted Jul 16, 2018 6:43 UTC (Mon) by cpitrat (subscriber, #116459) [Link] (4 responses)

Say people who do not use hundreds of billions of IR devices on their computer ...

IR decoding with BPF

Posted Jul 16, 2018 8:47 UTC (Mon) by paulj (subscriber, #341) [Link] (3 responses)

Interesting setup. How do you get billions of IR devices attached on a computer?

IR decoding with BPF

Posted Jul 16, 2018 8:59 UTC (Mon) by cpitrat (subscriber, #116459) [Link] (2 responses)

Billions is easy, I'm talking hundreds of billions.
First you have to buy them. That's where you discover that few sellers support int64 through their whole toolchain.
Then you have to get them deliver. Even with small packages (20 cm^3) we're talking about 20,000 trucks coming to your home.
Then you need longer cables because even if the receptor is only 1cm^3 you need a 32m radius sphere to fit them all (ignoring the cable).

So a bunch of challenges, but I as you see, no major obstacle.

IR decoding with BPF

Posted Jul 16, 2018 16:50 UTC (Mon) by excors (subscriber, #95769) [Link]

Why would you want a solid sphere of IR devices? You'd only be able to communicate with the ones on the outside surface, the others would all be in shadow. Surely you'd want to arrange them in a single layer as a spherical shell about 900m in radius, with your IR receiver in the middle. Then you might start to worry about decoding taking a noticeable percentage of your CPU cycles.

IR decoding with BPF

Posted Jul 19, 2018 8:56 UTC (Thu) by johnny (guest, #10110) [Link]

Is that really a productive use of your time, though? Wiring up the first hundred billion devices is probably a fun time, but I suspect the novelty would start wearing off soon thereafter.