From a28808e82bac1d5fa58cdd2a9ac86de361941529 Mon Sep 17 00:00:00 2001 From: Konstantin Khlebnikov Date: Thu, 25 Aug 2011 09:47:08 +1000 Subject: [PATCH] Use atomic-long operations instead of looping around cmpxchg(). Signed-off-by: Konstantin Khlebnikov Cc: Dave Chinner Signed-off-by: Andrew Morton --- include/linux/shrinker.h | 2 +- mm/vmscan.c | 17 +++++++---------- 2 files changed, 8 insertions(+), 11 deletions(-) diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h index 790651b4e5ba..ac6b8ee07825 100644 --- a/include/linux/shrinker.h +++ b/include/linux/shrinker.h @@ -34,7 +34,7 @@ struct shrinker { /* These are for internal use */ struct list_head list; - long nr; /* objs pending delete */ + atomic_long_t nr_in_batch; /* objs pending delete */ }; #define DEFAULT_SEEKS 2 /* A good number if you don't know better. */ extern void register_shrinker(struct shrinker *); diff --git a/mm/vmscan.c b/mm/vmscan.c index 17ff5f135d71..4fe6d72e951f 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -183,7 +183,7 @@ static unsigned long zone_nr_lru_pages(struct zone *zone, */ void register_shrinker(struct shrinker *shrinker) { - shrinker->nr = 0; + atomic_long_set(&shrinker->nr_in_batch, 0); down_write(&shrinker_rwsem); list_add_tail(&shrinker->list, &shrinker_list); up_write(&shrinker_rwsem); @@ -264,9 +264,7 @@ unsigned long shrink_slab(struct shrink_control *shrink, * and zero it so that other concurrent shrinker invocations * don't also do this scanning work. */ - do { - nr = shrinker->nr; - } while (cmpxchg(&shrinker->nr, nr, 0) != nr); + nr = atomic_long_xchg(&shrinker->nr_in_batch, 0); total_scan = nr; delta = (4 * nr_pages_scanned) / shrinker->seeks; @@ -328,12 +326,11 @@ unsigned long shrink_slab(struct shrink_control *shrink, * manner that handles concurrent updates. If we exhausted the * scan, there is no need to do an update. */ - do { - nr = shrinker->nr; - new_nr = total_scan + nr; - if (total_scan <= 0) - break; - } while (cmpxchg(&shrinker->nr, nr, new_nr) != nr); + if (total_scan > 0) + new_nr = atomic_long_add_return(total_scan, + &shrinker->nr_in_batch); + else + new_nr = atomic_long_read(&shrinker->nr_in_batch); trace_mm_shrink_slab_end(shrinker, shrink_ret, nr, new_nr); } -- 2.39.5