Re: [PATCH 2/3] broadcast-tick: Move oneshot broadcast mask to percpu variables

[Eric Dumazet]

Le vendredi 26 aoÃt 2011 Ã 15:32 -0700, Andi Kleen a Ãcrit :
> From: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> 
> Avoid a global cache line hotspot in the oneshot cpu mask. Maintain
> this information in per cpu variables instead.
> 
> Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> ---

>  
> -/* FIXME: use cpumask_var_t. */
> -static DECLARE_BITMAP(tick_broadcast_oneshot_mask, NR_CPUS);
> +struct broadcast_cpu_state {
> +	int need_oneshot;
> +} ____cacheline_aligned;
> +static DEFINE_PER_CPU(struct broadcast_cpu_state, state);

static DEFINE_PER_CPU_ALIGNED(...)

It avoids adding an alignment requirement on .data..percpu



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