Subject: Re: High resolution timers and BH processing on -RT
From: Thomas Gleixner <tglx@linutronix.de>
Reply-To: tglx@linutronix.de
To: Ingo Molnar <mingo@elte.hu>
Cc: George Anzinger <george@mvista.com>, LKML <linux-kernel@vger.kernel.org>,
       Doug Niehaus <niehaus@ittc.ku.edu>,
       Benedikt Spranger <bene@linutronix.de>
In-Reply-To: <20050128044301.GD29751@elte.hu>
References: <1106871192.21196.152.camel@tglx.tec.linutronix.de>
	 <20050128044301.GD29751@elte.hu>
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Date: Fri, 28 Jan 2005 09:20:10 +0100
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On Fri, 2005-01-28 at 05:43 +0100, Ingo Molnar wrote:
> * 
> is this due to algorithmic/PIT-programming overhead, or due to the noise
> introduced by other, non-hard-RT timers? I'd guess the later from the
> looks of it, but did your test introduce such noise (via networking and
> application workloads?).
> 

Right, it's due to noise by non-RT timers, which I enforced by adding
networking and applications.

This adds random timer expires and admittedly the PIT reprogramming
overhead is adding portions of that noise.

tglx


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