Re: RT patch acceptance

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Andrea Arcangeli wrote:
[...]
Plus with RTAI we don't depend on scheduler to do the right thing etc...
that suff can break when somebody tweak the scheduler for some smp
scalability bit or something like that (just watch currently Linus and
Ingo going after a scheduler bug that hangs the system, that would crash
a system with preempt-RT but RTAI would keep going without noticing
since it gets irq even when irqs are locally disabled), while it sounds
harder to break the nanokernel thing that depends on hardware feature
and unmaskable irqs.

It seems you didn't follow that thread too closely :)

The problem on that thread is that most of the processes running on the system have the same priority, and the way wine works is giving it an interactive priority bonus that makes it run preferentially over other processes with the "same" priority.

This wouldn't affect real-time tasks running over preempt-RT at all, since the interactive bonus would never be enough to go over real-time priority tasks.

I do understand the point you're trying to make about the simplicity of a nano-kernel that makes it much more reliable and verifiable.

However it seems that the range of applications that can use the nano-kernel approach is getting pretty thin between the applications that are so simple that they can run on a dedicated hardware/processor without any OS at all, and the applications that require more complex services than those that a nanokernel can provide by itself.

--
Paulo Marques - www.grupopie.com

An expert is a person who has made all the mistakes that can be
made in a very narrow field.
Niels Bohr (1885 - 1962)
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