Re: [PATCH 3/3 v3] mm/vmalloc: Cache the vmalloc memory info

From: Peter Zijlstra
Date: Tue Aug 25 2015 - 08:47:09 EST


On Sun, Aug 23, 2015 at 10:17:51AM +0200, Ingo Molnar wrote:
> +static u64 vmap_info_gen;
> +static u64 vmap_info_cache_gen;

> +void get_vmalloc_info(struct vmalloc_info *vmi)
> +{
> + u64 gen = READ_ONCE(vmap_info_gen);
> +
> + /*
> + * If the generation counter of the cache matches that of
> + * the vmalloc generation counter then return the cache:
> + */
> + if (READ_ONCE(vmap_info_cache_gen) == gen) {

Why are those things u64? It has the obvious down-side that you still
get split loads on 32bit machines.

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