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Date: Thu, 22 Jun 2006 00:35:14 +0100 (BST)
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To: Thomas Gleixner <tglx@linutronix.de>
cc: Esben Nielsen <nielsen.esben@googlemail.com>,
       Esben Nielsen <nielsen.esben@gogglemail.com>,
       Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@elte.hu>,
       linux-kernel@vger.kernel.org
Subject: Re: Why can't I set the priority of softirq-hrt? (Re: 2.6.17-rt1)
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From: Esben Nielsen <nielsen.esben@googlemail.com>
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On Wed, 21 Jun 2006, Thomas Gleixner wrote:

> On Wed, 2006-06-21 at 22:29 +0100, Esben Nielsen wrote:
>>> Find an version against the code in -mm below. Not too much tested yet.
>>
>> What if setscheduler is called from interrup context as in the hrt timers?
>
> It simply gets stuff going, nothing else.
>
What I mean is that we will then do the full priority inheritance boost 
with interrupts off.

Before setscheduler() was O(1), now it is O(<lock depth of what ever lock 
the target task might be locked on>).

This is not a problem for your use of setscheduler() as the task involved 
only can be blocked on kernel mutexes, but when the function is used on a 
userspace process the lock depth can be deep.


Esben


> 	tglx
>
>