Re: [PATCH] Don't export sched_mc_power_savings in laptops

From: Ingo Molnar
Date: Sun Nov 30 2008 - 12:41:07 EST



* Mahesh Salgaonkar <mahesh@xxxxxxxxxxxxxxxxxx> wrote:

> Fix to prevent sched_mc_power_saving from being exported through sysfs
> for multicore single socket (Laptop).
>
> CPU core map of the boot cpu should be equal to possible number
> of cpus for single socket system.
>
> This fix has been developed at FOSS.in kernel workout.
>
> Signed-off-by: Mahesh Salgaonkar <mahesh@xxxxxxxxxxxxxxxxxx>
>
> diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
> index 4850e4b..4adc830 100644
> --- a/arch/x86/include/asm/topology.h
> +++ b/arch/x86/include/asm/topology.h
> @@ -239,7 +239,7 @@ struct pci_bus;
> void set_pci_bus_resources_arch_default(struct pci_bus *b);
>
> #ifdef CONFIG_SMP
> -#define mc_capable() (boot_cpu_data.x86_max_cores > 1)
> +#define mc_capable() (cpus_weight(per_cpu(cpu_core_map,0)) != nr_cpu_ids)

hm, dunno. sched_mc_power_savings should have no effect on single-socket
systems, right? So the knob should have no effect.

Ingo
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