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    SubjectRe: [PATCH v7 4/4] nmi_backtrace: generate one-line reports for idle cpus
    On Mon 2016-08-15 12:41:54, Chris Metcalf wrote:
    > On 8/11/2016 11:25 AM, Petr Mladek wrote:
    > >On Mon 2016-08-08 12:03:38, Chris Metcalf wrote:
    > >>>>When doing an nmi backtrace of many cores, most of which are idle,
    > >>>>the output is a little overwhelming and very uninformative. Suppress
    > >>>>messages for cpus that are idling when they are interrupted and just
    > >>>>emit one line, "NMI backtrace for N skipped: idling at pc 0xNNN".
    > >Hmm, the problem is that native_safe_halt() is called from default_idle()
    > >here. The function is marked as inline but the compiler did not inline
    > >it.
    > >
    > >It helped me to put native_safe_halt() into the __cpuidle_text section:
    >
    > Following Peter Z's suggestion, I have added an __always_inline marker
    > to native_safe_halt. For consistency, I also did arch_safe_halt(), since that
    > invokes native_safe_halt, and then also native_halt() and halt(), so that
    > we're not being weirdly inconsistent with markings for halt inlines.
    >
    > There are also the native_irq_enable(), etc., accessors in that same header
    > that are still only marked "inline" not "always_inline", but I wanted to stop
    > before I was touching too much unrelated code.

    Sounds fine.

    > >I wonder if it would be possible to detect the idle thread an other
    > >way. For example, I wonder if it would be enough to check for the
    > >PID 0.
    >
    > No, the problem is that pid 0 can also go off and run "interesting" code
    > for things like power management, etc., so we really just want to
    > focus on being quite sure that the running code isn't interesting before
    > we suppress the backtrace information.
    >
    > See the thread around here:
    >
    > https://lkml.kernel.org/r/20160307204317.GR6344@twins.programming.kicks-ass.net

    Makes sense. Thanks for the poitner.

    Best Regards,
    Petr

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