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    SubjectRe: [RFC PATCH V4 2/5] cpuidle: list based cpuidle driver registration and selection
    * Trinabh Gupta <trinabh@linux.vnet.ibm.com> [2011-03-24 19:43:43]:


    [snip]

    > >>But we also have to replace the functionality provided by pm_idle,
    > >>i.e. call default_idle for platforms where no better idle routine
    > >>exists, call mwait for pre-nehalem platforms, use intel_idle or
    > >>acpi_idle for nehalem architectures etc. To manage all this
    > >>we need a registration mechanism which is conveniently provided
    > >>by cpuidle.
    > >
    > >It isn't immediately clear to me that all of these options
    > >need to be preserved.
    >
    > So what do you suggest can be removed?

    Can we use safe_halt() until intel_idle/acpi_idle take over? But what
    if they do not take over? If safe_halt() is not very bad compared to
    the variants like mwait_idle and c1e_idle, then we can remove the old
    code and no need to move them to default driver.

    > >Are we suggesting that x86 must always build with cpuidle?
    > >I'm sure that somebody someplace will object to that.
    >
    > Arjan argued that since almost everyone today runs cpuidle
    > it may be best to include it in the kernel
    > (https://lkml.org/lkml/2010/10/20/243). But yes, we agreed
    > that we would have to make cpuidle lighter incrementally.
    > Making ladder governor optional could be one way for example.
    > >
    > >OTOH, if cpuidle is included, I'd like to see the
    > >non-cpuidle code excluded, since nobody will run it...

    The non-cpuidle code will be the select_idle_routine() and related
    function that cam move to default_driver that register to cpuidle.
    We can load on-demand as module if better routines fail to register.
    Maybe we don't need this at all as discussed in the above point?

    --Vaidy

    [snip]



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