Re: [LAD] Litmus RT kernel

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To: Robin Gareus <robin@...>
Cc: Linux Audio Developers <linux-audio-dev@...>
Date: Saturday, March 5, 2011 - 3:27 pm

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On Sat, Mar 5, 2011 at 10:25 PM, Robin Gareus wrote:

>

> quick glance: I got the impression that it only addresses scheduling

Judging from the installation instructions, it seems preemption is there:

> cd litmus-rt

sane interface for assigning RT priviliges to non-root users. Then again,
that maybe covered to some degree in the provided liblitmus which in turn
provides:

rt_launch, which can be used to start arbitrary programs as real-time tasks.

If I get adventurous I may try compiling this thing to see what I can see.
Most of it is over my head and I'll take your word for it that this is far
from userland friendly or ready, but it looks like a fun learning exercise.

-m

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On Sat, Mar 5, 2011 at 10:25 PM, Robin Gareu=
s <robin@gareus.or=
g
> wrote:
=A0
quick glance: I got the impression that it only addresses scheduling
policy (task partitioning) and not realtime task preemption. Also
software needs to be written dedicated for Litmus RT.
Judging from the installation instructions, it se=
ems preemption is there:
cd litmus-rtpatch -p1 < ../litmus-rt-2011.1.pat=
ch# create a working kernel configuration# - select HZ=3D1000#=
- enable in-kernel preemptions# - disable NO_HZ# - don't us=
e power management options like frequency scaling
# - disable support for group scheduling# - disable "Write prote=
ct kernel read-only data structures" (in kernel debug)I got the feeling from reading that the main thing missing is some k=
ind of sane interface for assigning RT priviliges to non-root users. Then a=
gain, that maybe covered to some degree in the provided liblitmus which in =
turn provides:
rt_launch, wh=
ich can be used to start arbitrary programs as real-time tasks.
If I get adventurous I may try compiling this thing to see what I can s=
ee. Most of it is over my head and I'll take your word for it that this=
is far from userland friendly or ready, but it looks like a fun learning e=
xercise.
-m

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Messages in current thread:
[LAD] Litmus RT kernel, michael noble, (Thu Mar 3, 3:18 pm)
Re: [LAD] Litmus RT kernel, Robin Gareus, (Sat Mar 5, 1:25 pm)
Re: [LAD] Litmus RT kernel, michael noble, (Sat Mar 5, 3:27 pm)
Re: [LAD] Litmus RT kernel, Robin Gareus, (Sat Mar 5, 4:08 pm)