linux-kernel - Re: How how latent should non-preemptive scheduling be?

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Message-ID: <20080930112241.GC21367@elte.hu>
Date:	Tue, 30 Sep 2008 13:22:41 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Sitsofe Wheeler <sitsofe@...oo.com>
Cc:	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arjan van de Ven <arjan@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: How how latent should non-preemptive scheduling be?


* Sitsofe Wheeler <sitsofe@...oo.com> wrote:

>              cat-7717  [000]  1392.941867: __tasklet_schedule <-ath5k_intr
>              cat-7717  [000]  1393.005963: __tasklet_schedule <-ath5k_intr
>              cat-7717  [000]  1393.033222: __switch_to <-schedule
>
> Here a schedule seemingly doesn't happen for a few hundredths of a second...

that's about 60 msecs. ath5k_intr IRQ handling overhead? IRQ handlers 
are non-preemptible. (even under CONFIG_PREEMPT=y)

	Ingo
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