Re: [PATCH v3 12/32] shrinker: add node awareness

[Greg Thelen <gthelen@google.com>]

On Mon, Apr 08 2013, Glauber Costa wrote:

> From: Dave Chinner <dchinner@redhat.com>
>
> Pass the node of the current zone being reclaimed to shrink_slab(),
> allowing the shrinker control nodemask to be set appropriately for
> node aware shrinkers.
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
>  fs/drop_caches.c         |  1 +
>  include/linux/shrinker.h |  3 +++
>  mm/memory-failure.c      |  2 ++
>  mm/vmscan.c              | 12 +++++++++---
>  4 files changed, 15 insertions(+), 3 deletions(-)

I expected ashmem.c to get an update to ashmem_ioctl():

	case ASHMEM_PURGE_ALL_CACHES:
		ret = -EPERM;
		if (capable(CAP_SYS_ADMIN)) {
			struct shrink_control sc = {
				.gfp_mask = GFP_KERNEL,
				.nr_to_scan = 0,
			};

+			nodes_setall(sc.nodes_to_scan)

			ret = ashmem_shrink(&ashmem_shrinker, &sc);
			sc.nr_to_scan = ret;
			ashmem_shrink(&ashmem_shrinker, &sc);
		}
		break;
	}

>
> diff --git a/fs/drop_caches.c b/fs/drop_caches.c
> index c00e055..9fd702f 100644
> --- a/fs/drop_caches.c
> +++ b/fs/drop_caches.c
> @@ -44,6 +44,7 @@ static void drop_slab(void)
>  		.gfp_mask = GFP_KERNEL,
>  	};
>  
> +	nodes_setall(shrink.nodes_to_scan);
>  	do {
>  		nr_objects = shrink_slab(&shrink, 1000, 1000);
>  	} while (nr_objects > 10);
> diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
> index 4f59615..e71286f 100644
> --- a/include/linux/shrinker.h
> +++ b/include/linux/shrinker.h
> @@ -16,6 +16,9 @@ struct shrink_control {
>  
>  	/* How many slab objects shrinker() should scan and try to reclaim */
>  	long nr_to_scan;
> +
> +	/* shrink from these nodes */
> +	nodemask_t nodes_to_scan;
>  };
>  
>  /*
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index df0694c..857377e 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -248,10 +248,12 @@ void shake_page(struct page *p, int access)
>  	 */
>  	if (access) {
>  		int nr;
> +		int nid = page_to_nid(p);
>  		do {
>  			struct shrink_control shrink = {
>  				.gfp_mask = GFP_KERNEL,
>  			};
> +			node_set(nid, shrink.nodes_to_scan);
>  
>  			nr = shrink_slab(&shrink, 1000, 1000);
>  			if (page_count(p) == 1)
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 64b0157..6926e09 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2191,15 +2191,20 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
>  		 */
>  		if (global_reclaim(sc)) {
>  			unsigned long lru_pages = 0;
> +
> +			nodes_clear(shrink->nodes_to_scan);
>  			for_each_zone_zonelist(zone, z, zonelist,
>  					gfp_zone(sc->gfp_mask)) {
>  				if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
>  					continue;
>  
>  				lru_pages += zone_reclaimable_pages(zone);
> +				node_set(zone_to_nid(zone),
> +					 shrink->nodes_to_scan);
>  			}
>  
>  			shrink_slab(shrink, sc->nr_scanned, lru_pages);
> +
>  			if (reclaim_state) {
>  				sc->nr_reclaimed += reclaim_state->reclaimed_slab;
>  				reclaim_state->reclaimed_slab = 0;
> @@ -2778,6 +2783,8 @@ loop_again:
>  				shrink_zone(zone, &sc);
>  
>  				reclaim_state->reclaimed_slab = 0;
> +				nodes_clear(shrink.nodes_to_scan);
> +				node_set(zone_to_nid(zone), shrink.nodes_to_scan);
>  				nr_slab = shrink_slab(&shrink, sc.nr_scanned, lru_pages);
>  				sc.nr_reclaimed += reclaim_state->reclaimed_slab;
>  				total_scanned += sc.nr_scanned;
> @@ -3364,10 +3371,9 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
>  		 * number of slab pages and shake the slab until it is reduced
>  		 * by the same nr_pages that we used for reclaiming unmapped
>  		 * pages.
> -		 *
> -		 * Note that shrink_slab will free memory on all zones and may
> -		 * take a long time.
>  		 */
> +		nodes_clear(shrink.nodes_to_scan);
> +		node_set(zone_to_nid(zone), shrink.nodes_to_scan);
>  		for (;;) {
>  			unsigned long lru_pages = zone_reclaimable_pages(zone);

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