Re: [PATCH 1/2] scalable rw_mutex

[Oleg Nesterov <oleg@tv-sign.ru>]

On 05/12, Andi Kleen wrote:
> 
> --- linux-2.6.21-git2-net.orig/kernel/cpu.c
> +++ linux-2.6.21-git2-net/kernel/cpu.c
> @@ -26,6 +26,10 @@ static __cpuinitdata RAW_NOTIFIER_HEAD(c
>   */
>  static int cpu_hotplug_disabled;
>  
> +/* Contains any CPUs that were ever online at some point.
> +   No guarantee they were fully initialized though */
> +cpumask_t cpu_everonline_map;
> +
>  #ifdef CONFIG_HOTPLUG_CPU
>  
>  /* Crappy recursive lock-takers in cpufreq! Complain loudly about idiots */
> @@ -212,6 +216,8 @@ static int __cpuinit _cpu_up(unsigned in
>  	if (cpu_online(cpu) || !cpu_present(cpu))
>  		return -EINVAL;
>  
> +	cpu_set(cpu, cpu_everonline_map);
> +

This also allows us to de-uglify workqueue.c a little bit, it uses
a home-grown cpu_populated_map.

Oleg.

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