From: Ingo Molnar <mingo@elte.hu>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "Schultheiss, Christoph" <Christoph.Schultheiss@eurocopter.com>,
john stultz <johnstul@us.ibm.com>,
linux-kernel@vger.kernel.org
Subject: Re: duration of udelay differs with activated realtime-preempt patch?
Date: Fri, 25 Nov 2005 14:55:33 +0100 [thread overview]
Message-ID: <20051125135533.GA12823@elte.hu> (raw)
In-Reply-To: <1132925285.6694.9.camel@localhost.localdomain>
* Steven Rostedt <rostedt@goodmis.org> wrote:
> > 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?
yes, i found this problem too, a week ago or so. It's due to the GTOD
changes to i386's __delay() function. Does it still occur with -rt15
[which has the -B11 GTOD patchset] ?
Ingo
prev parent reply other threads:[~2005-11-25 13:55 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
2005-11-25 13:55 ` Ingo Molnar [this message]
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