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    SubjectRe: [PATCH] debugobjects: add a new Kconfig for POOL_SIZE
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    On 11/19/2018 08:27 AM, Qian Cai wrote:
    > On 11/19/18 at 3:09 AM, Thomas Gleixner wrote:
    >
    >> Qian,
    >>
    >> On Sun, 18 Nov 2018, Qian Cai wrote:
    >>>> On Nov 18, 2018, at 1:21 PM, Thomas Gleixner <tglx@linutronix.de> wrote:
    >>>> On Sun, 18 Nov 2018, Qian Cai wrote:
    >>>>> As the results, systems have 60+ CPUs with both timer and workqueue
    >>>>> objects enabled could trigger "ODEBUG: Out of memory. ODEBUG disabled".
    >>>>>
    >>>>> Hence, add a new Kconfig option so users could adjust ODEBUG_POOL_SIZE
    >>>>> accordingly if either timer or workqueue objects are selected.
    >>>> why do we need a config option, when the required number can be deduced
    >>>> already from the active CONFIG_DEBUG_OBJECTS_* and NR_CPUS?
    >>>>
    >>> It because I am worry about the coupling between the implementation details of
    >>> timers and workqueue objects, and the computation in the code you mentioned
    >>> here. For example, people could change workqueue.c to have different number
    >>> of worekqueues initialized during the early boot in the future which is going to
    >>> affect the required pool size, and I am not sure if people are going to adjust the
    >>> code in debugobjects.c here as well when they made changes like that.
    >>>
    >>> Also, the computation could become so complex depends on lots of config
    >>> options like perf, hrtimer, and combinations that I have not tested so far which is
    >>> difficult to exhausted all the possibilities.
    >>>
    >>> Hence, I feel like the Kconfig option is more flexible and less error-prone.
    >> Quite the contrary. Config options are a pain and truly error-prone if you
    >> want to compile general purpose kernels as distributions do.
    >>
    > Ah, I never thought distributions people would
    > enable those debugging options.

    Distros like RHEL usually ship two kernels - one for production and one
    for debug. The debug kernel does have debugobjects enabled.

    Cheers,
    Longman

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