Re: runsvdir polling

From: <39066dd5_at_gmail.com>
Date: Sun, 15 Jan 2017 13:58:30 -0800

On Sun, Jan 15, 2017 at 12:28:49PM -0500, Steve Litt wrote:
> > That sounds sensible on a desktop. In my case the motivation is to
> > trim a source of power draw for an image that's going to run on a
> > battery-powered device that will be awake but idle a lot of the time.
> > Why Linux? Pretty much familiarity & tooling, if power is ok then I
> > get to have my cake and eat it too.
>
> Why not try s6? IIRC, s6 doesn't poll, is a little more complex than
> runit, but like runit, it's a daemontools descendent. I've used it and
> like it.
>
> One thing to consider: What is the relationship between the 1m:55s and
> power consumed? Is power consumption proportional to CPU time, or does
> it depend on the kind of activity being done? Are disk accesses more,
> or less power hungry than loops with calculations or other CPU
> intensive stuff? How would you even find out the answers to these
> questons?
>
> Another question: What sized battery, is it rechargable, and how long
> do you expect it to last between replacements or recharges? What I'm
> getting at is this: If power draw is proportional to time, then in 50
> days runsvdir would have consumed just under 20 minutes, which is
> almost nothing if you're using a good sized battery.
>
> Are you going to use a superserver? This sounds like a good case for a
> superserver. You could use xinetd, or the djb-type superserver (can't
> remember its name).

I used s6 on a project last year and did like it. For this I'm using a distro (Void) that comes with runit as the standard init, switching would entail changes for third party services. Not all that bad but I'd like to avoid it if I can.

This project is really a meta-project. I have a handful of hobby projects where I want to be able to leave a computer in place and my hope is to use the same software toolchain as the starting point for each. I'm using a home media server as the training wheels project and then I have an interactive sculpture and a robotics project that will probably each be on Raspberry Pi or BeagleBone Black. The second two both look like a small machine with one long-lived control process hooked to camera, other sensors, and GPIO to control some hardware.

Realistically the runsvdir energy consumption is not going to be all that big but on the 1st run here it popped up as one of the top consumers of CPU on the dev machine. Having Linux & associated available tooling is great but I don't feel good about SysV init or a big Debian install being a critical part of the system.
Received on Sun Jan 15 2017 - 21:58:30 UTC