From: Steven Rostedt <rostedt@goodmis.org>
To: "Schultheiss, Christoph" <Christoph.Schultheiss@eurocopter.com>
Cc: john stultz <johnstul@us.ibm.com>, Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org
Subject: Re: duration of udelay differs with activated realtime-preempt patch?
Date: Fri, 25 Nov 2005 08:28:05 -0500 [thread overview]
Message-ID: <1132925285.6694.9.camel@localhost.localdomain> (raw)
In-Reply-To: <B7DA45CF87D412408436D5ECAAB9B90F6E7A06@sma2906.cr.eurocopter.corp>
On Fri, 2005-11-25 at 11:26 +0100, Schultheiss, Christoph wrote:
> kernel: 2.6.14 with and without the realtime-preempt patch
>
> hi list,
>
> after measuring the duration of the function udelay (with oscilloscope
> at parallel port), I figured out that udelay (5usec) with activated
> realtime- preempt patch lasts a little bit longer. Without the patch the
> time is exact.
> All kernel debug switches are turned off at compile time.
> Can anyone suggest why this happens?
Well, the -rt patch, has changed the udelay function. BTW, you are
using the constant udelay, right? Maybe an example of the code you used
to test might be useful.
Ingo or John?
-- Steve
next prev parent reply other threads:[~2005-11-25 13:28 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-25 10:26 duration of udelay differs with activated realtime-preempt patch? Schultheiss, Christoph
2005-11-25 13:28 ` Steven Rostedt [this message]
2005-11-25 13:55 ` Ingo Molnar
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