Message-ID: <1393563998.6018.19.camel@marge.simpson.net>
Subject: Re: [GIT PULL timers] Timer-wheel bandaids^Wcommits for 3.15
From: Mike Galbraith <bitbucket@online.de>
To: paulmck@linux.vnet.ibm.com
Cc: tglx@linutronix.de, mingo@kernel.org, linux-kernel@vger.kernel.org,
        josh@joshtriplett.org, peterz@infradead.org, oleg@redhat.com,
        rostedt@goodmis.org
Date: Fri, 28 Feb 2014 06:06:38 +0100
In-Reply-To: <20140228012704.GA20805@linux.vnet.ibm.com>
References: <20140228012704.GA20805@linux.vnet.ibm.com>
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Sender: linux-kernel-owner@vger.kernel.org

On Thu, 2014-02-27 at 17:27 -0800, Paul E. McKenney wrote: 
> Hello, Thomas and Ingo,
> 
> This pull request contains latency bandaids^Woptimizations to the
> timer-wheel code that are useful in conjunction with NO_HZ_FULL Kconfig
> option.  These optimizations reduce the jiffy-by-jiffy looping in cases
> where there is either zero or one timers in the timer wheel, which is
> a common case for NO_HZ_FULL "worker" CPUs that run almost entirely
> in usermode for a single task.

FWIW, these have seen quite a bit of runtime on various boxen, both in
day to day and piddle about -rt kernels, with zero attention grabbers.

-Mike

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