Re: report a bug about sched_rt
From: Peter Zijlstra
Date: Fri Jul 24 2009 - 09:13:22 EST
Don't top post -- again!
On Fri, 2009-07-24 at 21:04 +0800, sen wang wrote:
> Linux is used in many fieldes. SCHED_OTHER tasks is important to
> embedded system.
Irrelevant.
> if there is a running state taskïa realtime taskï, how can we
> shcedule the idle task up?
Because it ran out of bandwidth.
> It is ridiculousï
>
> since the throttle has a bug, why not fix it?
It doesn't have a bug, therefore I won't fix it.
The throttle limits the RT tasks to a bandwidth w of u/p.
Since real-time scheduling is about determinism a maximum bandwidth
larger than the minimum bandwidth specified by w is useless since it
cannot be relied upon.
Therefore we don't run RT tasks beyond their bandwidth limit.
Go read up on scheduling theory.
Now you might want a bandwidth of 100% for your RT application (not
something I can recommend for the overall health of your machine) in
which case you're free to change this setting:
echo -1 > /proc/sys/kernel/sched_rt_runtime_us
Should do that for you. Also read:
Documentation/scheduler/sched-rt-group.txt
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