Subject: Re: RT patch acceptance
From: Thomas Gleixner <tglx@linutronix.de>
Reply-To: tglx@linutronix.de
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Sven-Thorsten Dietrich <sdietrich@mvista.com>, Andi Kleen <ak@muc.de>,
       Ingo Molnar <mingo@elte.hu>, dwalker@mvista.com, bhuey@lnxw.com,
       hch@infradead.org, akpm@osdl.org, linux-kernel@vger.kernel.org
In-Reply-To: <4296D785.2050600@yahoo.com.au>
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Organization: linutronix
Date: Fri, 27 May 2005 12:17:40 +0200
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On Fri, 2005-05-27 at 18:17 +1000, Nick Piggin wrote:
> >>Or have I missed something completely? You RT guys have thought about
> >>it - so what are some pros of the Linux-RT patch and/or cons of the
> >>nanokernel approach, please?
>
> I never saw it happen in this forum. I believe you if you say it
> has, but I suspect a lot has changed since then.

It happened and mostly ended with a flame feast.

I try to give a very short and incomplete answer to a complex question.

Having RT features integrated in the kernel itself makes it simple to do
smooth transitions of applications from the soft-RT to the hard-RT world
without changing code, recompiling. You have one set of libraries
instead of two and perfect collocation of non-RT and RT threads. Users
have only to deal with one API instead of two.

Nanokernels give you slightly better latencies and make a clear
seperation between the RT and non RT world. This seperation is better
reviewable and gives you a chance to do static code path analysis in
order to do theoretical worst case estimation, which is a prerequisite
for approvals in certain application fields.

Theres a lot more - factual and "religious", but it takes more than a
few lines and a few minutes :)

I think there will be more application areas than the unpopular
industrial/embedded stuff in the near future which would benefit from
integrated RT enhancements.


tglx


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