linux-kernel - Re: [RFC] Introduce greedy hrtimer walk on idle

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Message-ID: <1317216203.24040.18.camel@twins>
Date:	Wed, 28 Sep 2011 15:23:23 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Venki Pallipadi <venki@...gle.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC] Introduce greedy hrtimer walk on idle

On Fri, 2011-09-23 at 16:47 -0700, Venki Pallipadi wrote:
> On Fri, Sep 23, 2011 at 1:03 PM, Peter Zijlstra <peterz@...radead.org> wrote:
> > On Fri, 2011-09-23 at 11:54 -0700, Venkatesh Pallipadi wrote:
> >> Comments?
> >
> > Looks to be a possible IRQ latency issue as well, that can be a lot of
> > timers to run..
> >
> 
> We could add some rate limit on how many timers we service this way
> and/or interrupt/disable-enable in the inner loop.
> But, this would be a problem with current hrtimer as well. When
> sched_tick timer is not around, we may end up servicing lot of timers
> depending on number of them and slack. No?

Right, still something to consider. We might just have to push down on
slack for -rt or so when it becomes a problem.
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