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Message-ID: <1325680229.2697.2.camel@twins>
Subject: Re: [PATCH]sched: stop hrtick timer if running task is switching
 from fair scheduling class to another
From: Peter Zijlstra <peterz@infradead.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Kirill Tkhai <kirill.tkhai@gmail.com>, linux-kernel@vger.kernel.org,
        Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
        Kirill Tkhai <tkhai@yandex.ru>
Date: Wed, 04 Jan 2012 13:30:29 +0100
In-Reply-To: <20111226154257.GA21445@redhat.com>
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	 <20111226154257.GA21445@redhat.com>
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On Mon, 2011-12-26 at 16:42 +0100, Oleg Nesterov wrote:
> 
> Peter, Ingo, does this code really work? SCHED_FEAT(HRTICK) == 0
> by default, and afaics you can't change it without CONFIG_SCHED_DEBUG.
> 
> 

No its broken. Maybe I should've removed it, but I've always been
meaning to fix it since SCHED_DEADLINE actually needs it, but alas.
-ENOTIME and no urgency need have conspired against it.