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    SubjectRe: Ftrace: can trace kthread?
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    On Thu, 2010-10-21 at 12:12 +0200, Peter Zijlstra wrote:
    > On Thu, 2010-10-21 at 16:59 +0800, Figo.zhang wrote:
    > > > I just
    > > > echo 0 > tracing_enabled

    I need to remove that file. "tracing_enabled" is pretty much deprecated,
    just use tracing_on to enable and disable the trace recording.

    > > > echo function > current_tracer
    > > > echo 374(pid of flush) > set_ftrace_pid
    > > > echo 1 > tracing_enabled
    > > > wait some time
    > > > echo 0 > tracing_enabled
    > > > cat trace
    > > >
    > > > So I think this answer your question "could kthread be traced?"
    > >
    > > i do it the same of you.
    >
    > > but i canot trace nothing.
    >
    > Your initial attempt had:
    >
    > echo kswapd > /sys/kernel/debug/tracing/set_graph_function

    Yeah, that wont work. That's because kswapd() is called at system
    startup and goes into a loop. The function graph tracer will never see
    that function again (it's not called again). It can't know what function
    it is in, only what functions it enters.

    -- Steve

    >
    > have you reset that state?




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