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    SubjectRe: [tip:x86/idle] x86, hotplug: Move WBINVD back outside the play_dead loop
    On 09/17/2010 05:48 PM, Venkatesh Pallipadi wrote:
    >> + wbinvd();
    >> +
    >> while (1) {
    >> - mb();
    >> - wbinvd();
    >> __monitor(&current_thread_info()->flags, 0, 0);
    >> mb();
    > Just one observation. There are some CPUs with errata that need
    > clflush before monitor. So, if that CPU wakesup spuriously it may have
    > problem reentering idle. Not sure whether that will be a problem as
    > that errata also depended on read happening on the flag. May be its
    > better to do monitor (0, 0, 0).

    It seems the easy way to deal with that would be to just add clflush
    before monitor... it is *probably* redundant, but it should be safe to
    do. It means depending on X86_FEATURE_CLFLUSH as well as
    X86_FEATURE_MWAIT, but I don't think there is any x86 processor which
    has MWAIT and not CLFLUSH, and I highly doubt there ever will be.

    Does anyone see any downside?


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