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Subject: Re: [RFC 3/4] Disable scheduler tick when we are running
 SCHED_FIFO tasks
From: Peter Zijlstra <peterz@infradead.org>
To: Jan Blunck <jblunck@suse.de>
Cc: Linux-Kernel Mailinglist <linux-kernel@vger.kernel.org>,
        linux-rt-users@vger.kernel.org,
        Sven-Thorsten Dietrich <sdietrich@novell.com>,
        Michael Galbraith <MGalbraith@novell.com>
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Date: Wed, 08 Sep 2010 14:45:43 +0200
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On Wed, 2010-09-08 at 14:29 +0200, Jan Blunck wrote:
> This patch is disabling the scheduler tick to go off when there is a task
> with SCHED_FIFO policy running. Since these tasks are not timesliced anyway
> we only care about timers, softirqs and such stuff just like when we disable
> the tick during idle periods.
> 

Also, doesn't this break any and all jiffies users?

And you need to restart the tick on call_rcu() and everything else that
requires the tick for processing.