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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 <andi@firstfloor.org> wrote:
    > Vikram Pandita <vikram.pandita@ti.com> writes:
    >
    >> From: Vikram Pandita <vikram.pandita@ti.com>
    >>
    >> 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: http://marc.info/?l=linux-omap&m=134401269106619&w=2

    > 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
    enabling: CONFIG_PRINTK_CPUID
    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
    >
    > --
    > ak@linux.intel.com -- Speaking for myself only


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