[CM] Watchdog unable to set SCHED_RT priority

Kjetil Matheussen k.s.matheussen at gmail.com
Tue Jul 13 10:57:38 PDT 2021


Hmm, I looked at the source code again, and it seems like the sound
player does run with realtime priority even when the watchdog can't
start. It's still not a problem though as modern computers usually
have more than one core plus that modern Linuxes should have a
built-in watchdog so that a single realtime thread shouldn't be able
to freeze the computer.

On Tue, Jul 13, 2021 at 7:40 AM Kenneth Flak <kennethflak at protonmail.com> wrote:
>
> Thanks! That was my intuition as well... I'm running snd with a buffer size of 1024, without any dropouts so far. In any case I'm not using snd for realtime work, so this is not a problem area.
>
> Best,
> Kenneth
>
> --
> Roosna & Flak - Contemporary Dance & Music
> Web: roosnaflak.com
> Code: {github,gitlab}.com/kflak
> Mastodon: @kf at sonomu.club
> On 13 Jul 2021  00:22, Kjetil Matheussen wrote:
> >No worries probably. In practice it only means that the sound player
> >won't run with realtime priortiy (since it couldn't start the watchdog
> >thread). If you don't get any dropouts in sound then that's not a
> >problem. I guess you get that error because you don't have privilege
> >to start a SCHED_RR thread with the highest possible priority, but
> >again, if you don't hear any dropouts, then you don't need it. When I
> >wrote the code around 2003 it might have been necessary to run with
> >realtime priority, but today I guess it's not.
> >
> >
> >On Mon, Jul 12, 2021 at 5:44 PM Kenneth Flak <kennethflak at protonmail.com> wrote:
> >>
> >> Hi list,
> >>
> >> I am getting this message when I exit snd:
> >>
> >> ```
> >> SNDLIB: Unable to set SCHED_RR realtime priority for the watchdog thread. No watchdog.
> >> SNDLIB: Watchdog exiting
> >> ```
> >> Is this a point of worry? My user should have realtime priviliges on my arch linux box...
> >>
> >> Best,
> >> Kenneth
> >>
> >> --
> >> Roosna & Flak - Contemporary Dance & Music
> >> Web: roosnaflak.com
> >> Code: {github,gitlab}.com/kflak
> >> Mastodon: @kf at sonomu.club
> >>
> >>
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>


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