From 125d98edd11464c8e0ec9eaaba7d682d0f832686 Mon Sep 17 00:00:00 2001 From: Coly Li Date: Fri, 24 Jan 2020 01:01:40 +0800 Subject: bcache: remove member accessed from struct btree The member 'accessed' of struct btree is used in bch_mca_scan() when shrinking btree node caches. The original idea is, if b->accessed is set, clean it and look at next btree node cache from c->btree_cache list, and only shrink the caches whose b->accessed is cleaned. Then only cold btree node cache will be shrunk. But when I/O pressure is high, it is very probably that b->accessed of a btree node cache will be set again in bch_btree_node_get() before bch_mca_scan() selects it again. Then there is no chance for bch_mca_scan() to shrink enough memory back to slub or slab system. This patch removes member accessed from struct btree, then once a btree node ache is selected, it will be immediately shunk. By this change, bch_mca_scan() may release btree node cahce more efficiently. Signed-off-by: Coly Li Signed-off-by: Jens Axboe --- drivers/md/bcache/btree.c | 8 ++------ drivers/md/bcache/btree.h | 2 -- 2 files changed, 2 insertions(+), 8 deletions(-) (limited to 'drivers/md') diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c index 14d6c33b0957..357535a5c89c 100644 --- a/drivers/md/bcache/btree.c +++ b/drivers/md/bcache/btree.c @@ -754,14 +754,12 @@ static unsigned long bch_mca_scan(struct shrinker *shrink, b = list_first_entry(&c->btree_cache, struct btree, list); list_rotate_left(&c->btree_cache); - if (!b->accessed && - !mca_reap(b, 0, false)) { + if (!mca_reap(b, 0, false)) { mca_bucket_free(b); mca_data_free(b); rw_unlock(true, b); freed++; - } else - b->accessed = 0; + } } out: mutex_unlock(&c->bucket_lock); @@ -1069,7 +1067,6 @@ retry: BUG_ON(!b->written); b->parent = parent; - b->accessed = 1; for (; i <= b->keys.nsets && b->keys.set[i].size; i++) { prefetch(b->keys.set[i].tree); @@ -1160,7 +1157,6 @@ retry: goto retry; } - b->accessed = 1; b->parent = parent; bch_bset_init_next(&b->keys, b->keys.set->data, bset_magic(&b->c->sb)); diff --git a/drivers/md/bcache/btree.h b/drivers/md/bcache/btree.h index 76cfd121a486..f4dcca449391 100644 --- a/drivers/md/bcache/btree.h +++ b/drivers/md/bcache/btree.h @@ -121,8 +121,6 @@ struct btree { /* Key/pointer for this btree node */ BKEY_PADDED(key); - /* Single bit - set when accessed, cleared by shrinker */ - unsigned long accessed; unsigned long seq; struct rw_semaphore lock; struct cache_set *c; -- cgit