[LAD] Litmus RT kernel

michael noble looplog at gmail.com
Sat Mar 5 15:26:54 UTC 2011

On Sat, Mar 5, 2011 at 10:25 PM, Robin Gareus <robin at gareus.org> wrote:


> 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 seems preemption is there:

> cd litmus-rt
> patch -p1 < ../litmus-rt-2011.1.patch
> # create a working kernel configuration
> #  - select HZ=1000
> #  - enable in-kernel preemptions
> #  - disable NO_HZ
> #  - don't use power management options like frequency scaling
> #  - disable support for group scheduling
> #  - disable "Write protect kernel read-only data structures" (in kernel debug)
> I got the feeling from reading that the main thing missing is some kind of
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

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.

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