Hi, thanks for the patch! I'll put this on our testing boxes... Are You going to push this upstream so we can ask Greg to push this to -stable? or do You plan to wait for more complex patch? n.
On Thu, Jul 21, 2011 at 02:24:58PM +0200, Peter Zijlstra wrote:
> On Thu, 2011-07-21 at 09:22 +0200, Ingo Molnar wrote:
> >
> > Ping, what's going on with this bug? Systems are crashing so we need
> > a quick fix ASAP ...
>
> Something as simple as the below ought to cure things for now. Once we
> get __cycles_2_ns() fixed up we can enable it again.
>
> (patch against -tip, .32 code is different but equally simple to fix)
>
> ---
> Subject: x86, intel: Don't mark sched_clock() as stable
>
> Because the x86 sched_clock() implementation wraps at 54 bits and the
> scheduler code assumes it wraps at the full 64bits we can get into
> trouble after 208 days (~7 months) of uptime.
>
> Signed-off-by: Peter Zijlstra <a.p.zijls...@chello.nl>
> ---
> arch/x86/kernel/cpu/intel.c | 7 +++++++
> 1 files changed, 7 insertions(+), 0 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
> index ed6086e..c8dc48b 100644
> --- a/arch/x86/kernel/cpu/intel.c
> +++ b/arch/x86/kernel/cpu/intel.c
> @@ -91,8 +91,15 @@ static void __cpuinit early_init_intel(struct cpuinfo_x86
> *c)
> if (c->x86_power & (1 << 8)) {
> set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
> set_cpu_cap(c, X86_FEATURE_NONSTOP_TSC);
> + /*
> + * Unfortunately our __cycles_2_ns() implementation makes
> + * the raw sched_clock() interface wrap at 54-bits, which
> + * makes it unsuitable for direct use, so disable this
> + * for now.
> + *
> if (!check_tsc_unstable())
> sched_clock_stable = 1;
> + */
> }
>
> /*
>
>
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