diff options
| -rw-r--r-- | include/linux/shrinker.h | 38 | ||||
| -rw-r--r-- | mm/vmscan.c | 60 |
2 files changed, 29 insertions, 69 deletions
diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h index 884e76222..ac6b8ee07 100644 --- a/include/linux/shrinker.h +++ b/include/linux/shrinker.h @@ -4,12 +4,6 @@ /* * This struct is used to pass information from page reclaim to the shrinkers. * We consolidate the values for easier extention later. - * - * The 'gfpmask' refers to the allocation we are currently trying to - * fulfil. - * - * Note that 'shrink' will be passed nr_to_scan == 0 when the VM is - * querying the cache size, so a fastpath for that case is appropriate. */ struct shrink_control { gfp_t gfp_mask; @@ -18,37 +12,23 @@ struct shrink_control { unsigned long nr_to_scan; }; -#define SHRINK_STOP (~0UL) /* * A callback you can register to apply pressure to ageable caches. * - * @shrink() should look through the least-recently-used 'nr_to_scan' entries - * and attempt to free them up. It should return the number of objects which - * remain in the cache. If it returns -1, it means it cannot do any scanning at - * this time (eg. there is a risk of deadlock). + * 'sc' is passed shrink_control which includes a count 'nr_to_scan' + * and a 'gfpmask'. It should look through the least-recently-used + * 'nr_to_scan' entries and attempt to free them up. It should return + * the number of objects which remain in the cache. If it returns -1, it means + * it cannot do any scanning at this time (eg. there is a risk of deadlock). * - * @count_objects should return the number of freeable items in the cache. If - * there are no objects to free or the number of freeable items cannot be - * determined, it should return 0. No deadlock checks should be done during the - * count callback - the shrinker relies on aggregating scan counts that couldn't - * be executed due to potential deadlocks to be run at a later call when the - * deadlock condition is no longer pending. + * The 'gfpmask' refers to the allocation we are currently trying to + * fulfil. * - * @scan_objects will only be called if @count_objects returned a non-zero - * value for the number of freeable objects. The callout should scan the cache - * and attempt to free items from the cache. It should then return the number - * of objects freed during the scan, or SHRINK_STOP if progress cannot be made - * due to potential deadlocks. If SHRINK_STOP is returned, then no further - * attempts to call the @scan_objects will be made from the current reclaim - * context. + * Note that 'shrink' will be passed nr_to_scan == 0 when the VM is + * querying the cache size, so a fastpath for that case is appropriate. */ struct shrinker { int (*shrink)(struct shrinker *, struct shrink_control *sc); - unsigned long (*count_objects)(struct shrinker *, - struct shrink_control *sc); - unsigned long (*scan_objects)(struct shrinker *, - struct shrink_control *sc); - int seeks; /* seeks to recreate an obj */ long batch; /* reclaim batch size, 0 = default */ diff --git a/mm/vmscan.c b/mm/vmscan.c index 704d97bb2..fef051303 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -268,24 +268,19 @@ static inline int do_shrinker_shrink(struct shrinker *shrinker, * * Returns the number of slab objects which we shrunk. */ -unsigned long shrink_slab(struct shrink_control *shrinkctl, +unsigned long shrink_slab(struct shrink_control *shrink, unsigned long nr_pages_scanned, unsigned long lru_pages) { struct shrinker *shrinker; - unsigned long freed = 0; + unsigned long ret = 0; if (nr_pages_scanned == 0) nr_pages_scanned = SWAP_CLUSTER_MAX; if (!down_read_trylock(&shrinker_rwsem)) { - /* - * If we would return 0, our callers would understand that we - * have nothing else to shrink and give up trying. By returning - * 1 we keep it going and assume we'll be able to shrink next - * time. - */ - freed = 1; + /* Assume we'll be able to shrink next time */ + ret = 1; goto out; } @@ -293,16 +288,14 @@ unsigned long shrink_slab(struct shrink_control *shrinkctl, unsigned long long delta; long total_scan; long max_pass; + int shrink_ret = 0; long nr; long new_nr; long batch_size = shrinker->batch ? shrinker->batch : SHRINK_BATCH; - if (shrinker->count_objects) - max_pass = shrinker->count_objects(shrinker, shrinkctl); - else - max_pass = do_shrinker_shrink(shrinker, shrinkctl, 0); - if (max_pass == 0) + max_pass = do_shrinker_shrink(shrinker, shrink, 0); + if (max_pass <= 0) continue; /* @@ -318,8 +311,8 @@ unsigned long shrink_slab(struct shrink_control *shrinkctl, do_div(delta, lru_pages + 1); total_scan += delta; if (total_scan < 0) { - printk(KERN_ERR - "shrink_slab: %pF negative objects to delete nr=%ld\n", + printk(KERN_ERR "shrink_slab: %pF negative objects to " + "delete nr=%ld\n", shrinker->shrink, total_scan); total_scan = max_pass; } @@ -347,33 +340,20 @@ unsigned long shrink_slab(struct shrink_control *shrinkctl, if (total_scan > max_pass * 2) total_scan = max_pass * 2; - trace_mm_shrink_slab_start(shrinker, shrinkctl, nr, + trace_mm_shrink_slab_start(shrinker, shrink, nr, nr_pages_scanned, lru_pages, max_pass, delta, total_scan); while (total_scan >= batch_size) { + int nr_before; - if (shrinker->scan_objects) { - unsigned long ret; - shrinkctl->nr_to_scan = batch_size; - ret = shrinker->scan_objects(shrinker, shrinkctl); - - if (ret == SHRINK_STOP) - break; - freed += ret; - } else { - int nr_before; - long ret; - - nr_before = do_shrinker_shrink(shrinker, shrinkctl, 0); - ret = do_shrinker_shrink(shrinker, shrinkctl, - batch_size); - if (ret == -1) - break; - if (ret < nr_before) - freed += nr_before - ret; - } - + nr_before = do_shrinker_shrink(shrinker, shrink, 0); + shrink_ret = do_shrinker_shrink(shrinker, shrink, + batch_size); + if (shrink_ret == -1) + break; + if (shrink_ret < nr_before) + ret += nr_before - shrink_ret; count_vm_events(SLABS_SCANNED, batch_size); total_scan -= batch_size; @@ -391,12 +371,12 @@ unsigned long shrink_slab(struct shrink_control *shrinkctl, else new_nr = atomic_long_read(&shrinker->nr_in_batch); - trace_mm_shrink_slab_end(shrinker, freed, nr, new_nr); + trace_mm_shrink_slab_end(shrinker, shrink_ret, nr, new_nr); } up_read(&shrinker_rwsem); out: cond_resched(); - return freed; + return ret; } static inline int is_page_cache_freeable(struct page *page) |