Messages in this thread | | | Date | Wed, 11 Dec 2013 20:49:41 -0800 | From | "H. Peter Anvin" <> | Subject | Re: 50 Watt idle power regression bisected to Linux-3.10 |
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On 12/11/2013 08:25 PM, Mike Galbraith wrote: > arch/x86/include/asm/mwait.h | 4 ++-- > arch/x86/kernel/cpu/common.c | 7 ++++--- > arch/x86/kernel/setup_percpu.c | 1 + > 3 files changed, 7 insertions(+), 5 deletions(-) > > Index: linux-2.6/arch/x86/kernel/cpu/common.c > =================================================================== > --- linux-2.6.orig/arch/x86/kernel/cpu/common.c > +++ linux-2.6/arch/x86/kernel/cpu/common.c > @@ -65,13 +65,14 @@ void __init setup_cpu_local_masks(void) > } > > /* allocate percpu area for mwait doorbell */ > -char __percpu *mwait_doorbell; > +DEFINE_PER_CPU(char *, mwait_doorbell); > +EXPORT_PER_CPU_SYMBOL(mwait_doorbell); >
Sorry, this is wrong. This is NOT a percpu variable, it is a pointer to a percpu allocation, but the variable itself is not a percpu variable. This explains your boom.
> void __init setup_mwait_doorbell(void) > { > if (boot_cpu_has(X86_FEATURE_MWAIT)) { > - mwait_doorbell = __alloc_percpu(boot_cpu_data.clflush_size, > - boot_cpu_data.clflush_size); > + mwait_doorbell = __alloc_percpu(boot_cpu_data.x86_clflush_size, > + boot_cpu_data.x86_clflush_size); > > if (!mwait_doorbell) { > /* This should never happen... */
-hpa
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