Newbie question about profiling.

[Lars Segerlund <lars.segerlund@gmail.com>]

 Hello,

 I am fairly new to RT Preempt, but now to realtime embedded systems.
I am trying to get EMC2 running on RT Preempt, and I was given some
old patches on the mailing list which miracously worked.

 From here I am trying to get a complete system built from scratch
with 'latest' RT Preempt and EMC2.

 My question is how to go about finding out what causes latencies and
jitter, I have no problem to create some code to benchmark latencies
or jitter, but how do I find out where the kernel is spending it's
time ?

 Any hints would be much appreciated, since i really don't have a clue
on how to go about this.

 I was thinking that if I could create a realtime task to test for a
specific thing, I really would like a log of what the kernal was doing
right before this.
 The only way I can think of is creating a module with a ring buffer (
spill over ), and tracing the scheduler or interrupt handler .... ( by
hackíng some code to specifically do this ), this would only add a
small overhead AFAIK.

 Any idea's anyone ? or hints ?

 It seem's like just the thing that already might have a solution in
place, so I figured I should not reinvent the wheel.

 / best regards, Lars Segerlund.
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