Re: [PATCH] page_alloc: skip cpuset enforcement for lower zone allocations (v3)

[Christoph Lameter]

On Wed, 28 May 2014, Marcelo Tosatti wrote:

> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 5dba293..dfea3dc 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2698,6 +2698,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
>  	unsigned int cpuset_mems_cookie;
>  	int alloc_flags = ALLOC_WMARK_LOW|ALLOC_CPUSET|ALLOC_FAIR;
>  	struct mem_cgroup *memcg = NULL;
> +	nodemask_t *cpuset_mems_allowed = &cpuset_current_mems_allowed;

Why do you need this one?

>  	gfp_mask &= gfp_allowed_mask;
>
> @@ -2726,9 +2727,14 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
>  retry_cpuset:
>  	cpuset_mems_cookie = read_mems_allowed_begin();
>
> +#ifdef CONFIG_NUMA
> +	if (gfp_zone(gfp_mask) < policy_zone)
> +		cpuset_mems_allowed = NULL;

nodemask = &node_states[N_ONLINE];

> +#endif


> +
>  	/* The preferred zone is used for statistics later */
>  	first_zones_zonelist(zonelist, high_zoneidx,
> -				nodemask ? : &cpuset_current_mems_allowed,
> +				nodemask ? : cpuset_mems_allowed,

Skip this?

>  				&preferred_zone);
>  	if (!preferred_zone)
>  		goto out;
>

Why call __alloc_pages_nodemask at all if you want to skip the node
handling? Punt to alloc_pages()
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