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    SubjectRe: [PATCH 6/6] tracing/fastboot: Print ktime of sched events when boot tracing
    2008/10/10 Ingo Molnar <mingo@elte.hu>:
    >
    > * Frederic Weisbecker <fweisbec@gmail.com> wrote:
    >
    >> When we use the boot tracer, we want the sched events to be printed
    >> with the same timestamp than initcall events. So we have to create a
    >> new type of entry which contains sched event attributes and the ktime
    >> of the creation of the entry. Then the output is handled by the boot
    >> tracer.
    >
    > hm, i think that's unnecessary duplication. Please extend the context
    > switch trace entries to be useful for the boot tracer as well:
    >

    Ok. I will change it in V2.

    > also, ktime_get() can be a quite complex function with dependency on
    > xtime_lock - that inverts with the rq lock - so this can lock up
    > sporadically when called from within the scheduler.
    > it would be _much_ simpler to standardize the initcall timestamps on
    > cpu_clock() instead. That too is a good global clock and starts at zero
    > during bootup. Ok?

    Hmm. Ok, I will pick what I saw about cpu_clock() in printk.c

    > Your other patches look good and i've applied them to
    > tip/tracing/fastboot:
    >
    > 3981ce9: tracing/fastboot: use sched switch tracer from boot tracer
    > 563582a: tracing/ftrace: remove unused code in sched_switch tracer
    > d25b1ce: tracing/ftrace: fix a race condition in sched_switch tracer

    Thanks. But are you really sure about d25b1ce?
    Steven suggested some changes. But it doesn't matter, I can apply his
    suggestions on top of this applied patch.


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