Re: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm3-V0.7.32-15

From: Ingo Molnar
Date: Fri Dec 10 2004 - 16:12:25 EST

* Mark_H_Johnson@xxxxxxxxxxxx <Mark_H_Johnson@xxxxxxxxxxxx> wrote:

> [1] I still do not get traces where cpu_delay switches CPU's. I only
> get trace output if it starts and ends on a single CPU. [...]

lt001.18RT/lt.02 is such a trace. It starts on CPU#1:

<unknown-3556 1...1 0µs : find_next_bit (user_trace_start)

and ends on CPU#0:

<unknown-3556 1...1 247µs : _raw_spin_lock_irqsave (user_trace_stop)

the trace shows a typical migration of an RT task.

(but ... i have to say the debugging overhead is horrible. Please try a
completely-non-debug-non-tracing kernel just to see the difference.)

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