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    SubjectRe: [PATCH 13/15] sched: Use a static_key for sched_clock_stable
    On 2014.01.22 at 19:42 +0100, Peter Zijlstra wrote:
    > On Wed, Jan 22, 2014 at 07:35:38PM +0100, Markus Trippelsdorf wrote:
    >
    > > >FYI it happens on real hardware on my machine:
    >
    > > >[ 60.375384] process: using AMD E400 aware idle routine
    >
    > > But this is a different issue. I've bisected it to:
    > >
    > > commit 20d1c86a57762f0a33a78988e3fc8818316badd4
    > > Author: Peter Zijlstra <peterz@infradead.org>
    > > Date: Fri Nov 29 15:40:29 2013 +0100
    > >
    > > sched/clock, x86: Rewrite cyc2ns() to avoid the need to disable IRQs
    > >
    > > Reverting the commit "fixes" the issue:
    >
    > Hurm..

    Turns out the fix is simple:

    diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
    index a3acbac2ee72..d90f7a11d573 100644
    --- a/arch/x86/kernel/tsc.c
    +++ b/arch/x86/kernel/tsc.c
    @@ -1198,8 +1198,8 @@ void __init tsc_init(void)
    * up if their speed diverges)
    */
    for_each_possible_cpu(cpu) {
    - cyc2ns_init(cpu);
    set_cyc2ns_scale(cpu_khz, cpu);
    + cyc2ns_init(cpu);
    }

    if (tsc_disabled > 0)
    --
    Markus


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