duration of udelay differs with activated realtime-preempt patch?

From: Schultheiss, Christoph
Date: Fri Nov 25 2005 - 05:31:34 EST


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?

christoph
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