From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Christian Kraus <chk.dax@gmx.de>
Cc: linux-rt-users <linux-rt-users@vger.kernel.org>
Subject: Re: Interrupt Latency 2.6.33.7 rt30
Date: Fri, 26 Aug 2011 09:48:36 +0200 [thread overview]
Message-ID: <20110826074836.GO16557@pengutronix.de> (raw)
In-Reply-To: <4E56B8A5.6080306@gmx.de>
On Thu, Aug 25, 2011 at 11:03:33PM +0200, Christian Kraus wrote:
> Hello
> I have wrote a GPIO-driver, that toggle the value of a GPIO when a
> interrupt is comming from an another GPIO.
> When I measure the latency between the interrupt and the toggled Pin
> it's about ten times higher than without the rt-patch.
> (without Patch = 8-11 us
> with Patch = 30-110 us)
It's expected and known that an rt kernel has a worse average latency.
Having said that I cannot say if the increase you see is "too much".
The best option you have is asking ftrace what happens in these 30-110
us after making sure you have a decent sched_clock implementation.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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next prev parent reply other threads:[~2011-08-26 7:48 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-25 21:03 Interrupt Latency 2.6.33.7 rt30 Christian Kraus
2011-08-26 7:48 ` Uwe Kleine-König [this message]
2011-09-01 19:11 ` Thomas Gleixner
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