From: Jan Blunck <jblunck@novell.com>
To: Peter Zijlstra <peterz@infradead.org>
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>
Subject: Re: [RFC 3/4] Disable scheduler tick when we are running SCHED_FIFO tasks
Date: Wed, 8 Sep 2010 16:28:26 +0200 [thread overview]
Message-ID: <20100908142826.GI7436@bolzano.suse.de> (raw)
In-Reply-To: <1283949943.23762.16.camel@laptop>
On Wed, Sep 08, Peter Zijlstra wrote:
> 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?
>
Sure. It was enough to make FTQ run.
> And you need to restart the tick on call_rcu() and everything else that
> requires the tick for processing.
>
I realized that before as well but somehow forgot about it. Checking for a
disabled timer tick on syscall entry would help. Like we do on irq entry as
well.
Jan
next prev parent reply other threads:[~2010-09-08 14:28 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-08 12:29 [RFC 0/4] Disable timer tick for " Jan Blunck
2010-09-08 12:29 ` [RFC 1/4] ftrace: Add events for tracing timer interrupts Jan Blunck
2010-09-08 12:38 ` Peter Zijlstra
2010-09-08 13:24 ` Andi Kleen
2010-09-08 12:29 ` [RFC 2/4] ftrace: Add events for tracing tick start and stop Jan Blunck
2010-09-08 12:29 ` [RFC 3/4] Disable scheduler tick when we are running SCHED_FIFO tasks Jan Blunck
2010-09-08 12:43 ` Peter Zijlstra
2010-09-08 14:32 ` Jan Blunck
2010-09-08 12:45 ` Peter Zijlstra
2010-09-08 13:21 ` Thomas Gleixner
2010-09-08 14:28 ` Jan Blunck [this message]
2010-09-08 17:11 ` Andi Kleen
2010-09-08 13:25 ` Andi Kleen
2010-09-08 14:47 ` Jan Blunck
2010-09-08 12:29 ` [RFC 4/4] ftrace: Add argument to tick start/stop tracing Jan Blunck
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