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    SubjectRe: [PATCH v3] printk: add option to print cpu id
    On Fri, Aug 3, 2012 at 10:54 AM, Andi Kleen <> wrote:
    > Vikram Pandita <> writes:
    >> From: Vikram Pandita <>
    >> Introduce config option to enable CPU id reporting for printk() calls.
    > What's wrong with using trace_printk for this?

    trace_printk works only when you know the _exact_ path in code that
    you want to profile.
    When you have no idea of a random lockup, then it would be kind of
    touch and time consuming
    to put trace prints all around the code.

    > That's much faster
    > anyways. Generally printk is so slow that it's typically useless for
    > instrumenting races.

    As stated in another thread, its found useful to debug some specific cases:
    Check thread:

    > And really: Wasting 1/3 of the 80 character line is too much.

    You _WASTE_ 4 chars only if you are interested in this info by
    Just like you _WASTE_ 15 chars when you enable existing: CONFIG_PRINTK_TIME

    For general usecase, recommendation would be to keep these options disabled.
    Working on shipping products, i find almost all shipping with
    CONFIG_PRINTK_TIME enabled, so there must be some value.
    Same would hold for the use case being debugged for CPUID enabling.

    > -Andi
    > --
    > -- Speaking for myself only

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