Re: runsvdir polling

From: Steve Litt <>
Date: Sat, 14 Jan 2017 16:10:07 -0500

On Fri, 13 Jan 2017 21:12:27 -0800 wrote:

> I'm using runit as my primary init on Linux to good effect but have
> noticed that it accumulates CPU time even while the system is idle. I
> suspect that this is a consequence of runsvdir polling the service
> directory for changes and that using inotify would reduce this. This
> would introduce some complexity and variance between platforms but
> bring the benefit of removing a source of CPU wake-ups. Has using
> inotify been considered and rejected for another reason?

How much time in how much uptime? Which process are you looking at with
this accumulated time? Here's what I get:

[slitt_at_mydesk ~]$ ps ax | grep run | grep -v 0:00
    1 ? Ss 2:07 runit
  693 ? Ss 32:59 runsvdir -P /run/runit/runsvdir/current log:
c: Module load failed. E: [pulseaudio] main.c: Failed to initialize
daemon. Traceback (most recent call last): File
"/d/at/python/reminder_check/", line 6, in
<module> import tkinter ImportError: No module named 'tkinter'
Traceback (most recent call last): File "/d/bats/", line
9, in <module> from tkinter import * ImportError: No module named

709 ? Ss 12:19 runsv supervise
711 ? Ss 12:44 runsv wpa_supplicant
720 ? Ss 12:52 runsv pulseaudio
722 ? Ss 21:06 runsv reminder_check
723 ? Ss 12:06 runsv current
[slitt_at_mydesk ~]$

That's a total of roughly 1 hour and 45 minutes. Now consider my uptime:

[slitt_at_mydesk ~]$ uptime
 15:51:03 up 13 days, 2:35, 1 user, load average: 0.28, 0.32, 0.35
[slitt_at_mydesk ~]$

That means my runit time is 0.56 of the time my computer's been up. I
can easily live with that for the simplicity benefit of runit,
including the fact that it polls.

Besides, a lot of the runsv's had times of 0, including the ones for
the virtual terminals. Of the ones that had times, a lot were
supervising iffy apps, such as pulseaudio, wpa_supplicant, which
terminates at the drop of a hat, and reminder_check, a home-grown
Python reminder system that I run as a daemon, and which I never tested
for stability.

I wouldn't care to guess how much time these apps would consume
supervising or respawning with other init systems.

On my computer, none of this in any practical way affects my computing.
I would guess on a more heavily used computer, any deleterious effects
of runit time consumption could be solved by running runsvdir and all
the runsv's with a positive nice value.

In my opinion, by far the greatest benefit of runit is its simplicity,
and there's no way I'd trade that for a theoretical efficiency benefit.


Steve Litt
January 2017 featured book: Troubleshooting: Just the Facts
Received on Sat Jan 14 2017 - 21:10:07 UTC

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