Re: duration of udelay differs with activated realtime-preemptpatch?

[Steven Rostedt]

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


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