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Date: Wed, 06 Feb 2008 10:04:46 -0800
From: Max Krasnyanskiy <maxk@qualcomm.com>
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To: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Steven Rostedt <srostedt@redhat.com>, Ingo Molnar <mingo@elte.hu>,
       LKML <linux-kernel@vger.kernel.org>
Subject: Re: RT scheduler config, suggestions and questions
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Peter Zijlstra wrote:
> On Wed, 2008-02-06 at 07:36 +0100, Peter Zijlstra wrote:
> 
>>> btw I can see "watchdog" being very useful to catch hard-RT tasks that exceed the deadline.
>>> But's it gotta be per thread.
>> It is.
>>
>>> Single setting per user is not enough. Unless a use has a single RT task.
>> ?
> 
> Ah, its starting to make sense, you want it configurable per thread, not
> process wide. Yes, I see how that is useful, just no idea how to expose
> that to user-space atm.
Yes. That's what I meant. I don't think overall per process setting is that useful.
Per thread though would be useful.

How to expose that to the user-space ? The best option in my opinion is to extend
struct sched_param. That way both sched_setparam() and pthread_attr_setschedparam() 
can be used to set new attributes and it's backwards compatible.
Something like:

struct sched_param {
	...
	unsigned int sched_rt_limit;
	unsigned int sched_rt_...;
};

Max