[Rtai] Interrupt latency problem

[mj]

Hello Everyone!
    I'm a freshman in this field.Now I get a big problem,and I hope someone can give me some advice.
    After I installed linux2.6.23.14(ubuntu amd64 8.04)+rtai3.6  on my Pc(athlon64 3600+,C61 mainboard),I used the tool /usr/realtime/calibration/calibrate -i.The result is:
*** NUMBER OF REQUESTS: 1. ***

->>> INTERRUPT LATENCY CHECK (press enter to end check) <<<-

2008/05/21-09:40:51 -> 3900.162 (us)
2008/05/21-09:40:51 -> 3900.711 (us)
2008/05/21-09:40:51 -> 3900.834 (us)
2008/05/21-09:40:53 -> 3901.689 (us)
2008/05/21-09:40:57 -> 3902.890 (us)

I saw somebody had mentioned:
Modify calibration_helper.c to use isolcpus.
But,I didn't know how to do this step.Is there anyone could tell how to do this?
Or I should do some other things?
Hope to hear from you soon!Thanks in advance!
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