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    SubjectRe: [PATCH] perf/x86: check ucode before disabling PEBS on SandyBridge
    On Fri, 2012-06-08 at 16:15 +0200, Borislav Petkov wrote:
    > have a variable which gets initialized to the number of all CPUs and
    > each time ->apply_microcode() finishes by returning 0, we decrement it
    > once.

    > Hmm, I'm probably missing some obscure case.

    Since its all per-cpu sysfs muck, userspace could update a random
    subsets of cpus.. leaving us hanging.

    The 'bestestet' idea I came up with is doing the verify thing I have
    from a delayed work -- say 1 second into the future. That way, when
    there's lots of cpus they all try and enqueue the one work, which at the
    end executes only once, provided the entire update scan took less than
    the second.

    But yuck..

     \ /
      Last update: 2012-06-08 17:01    [W:0.020 / U:6.732 seconds]
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