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authorColy Li <colyli@suse.de>2020-07-25 20:00:37 +0800
committerJens Axboe <axboe@kernel.dk>2020-07-25 07:38:21 -0600
commit6907dc498f79543e5a32e632135e51b960331316 (patch)
treecf15002aca33b45d53abd8ee8939d05402849f6e /drivers/md
parent092bd54d69230b4a4a7f640a4cdcdeb004d3546e (diff)
downloadlinux-6907dc498f79543e5a32e632135e51b960331316.tar.bz2
bcache: avoid extra memory allocation from mempool c->fill_iter
Mempool c->fill_iter is used to allocate memory for struct btree_iter in bch_btree_node_read_done() to iterate all keys of a read-in btree node. The allocation size is defined in bch_cache_set_alloc() by, mempool_init_kmalloc_pool(&c->fill_iter, 1, iter_size)) where iter_size is defined by a calculation, (sb->bucket_size / sb->block_size + 1) * sizeof(struct btree_iter_set) For 16bit width bucket_size the calculation is OK, but now the bucket size is extended to 32bit, the bucket size can be 2GB. By the above calculation, iter_size can be 2048 pages (order 11 is still accepted by buddy allocator). But the actual size holds the bkeys in meta data bucket is limited to meta_bucket_pages() already, which is 16MB. By the above calculation, if replace sb->bucket_size by meta_bucket_pages() * PAGE_SECTORS, the result is 16 pages. This is the size large enough for the mempool allocation to struct btree_iter. Therefore in worst case every time mempool c->fill_iter allocates, at most 4080 pages are wasted and won't be used. Therefore this patch uses meta_bucket_pages() * PAGE_SECTORS to calculate the iter size in bch_cache_set_alloc(), to avoid extra memory allocation from mempool c->fill_iter. Signed-off-by: Coly Li <colyli@suse.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/bcache/super.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 62c9681fe92f..c6b6276cada8 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1916,7 +1916,7 @@ struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)
INIT_LIST_HEAD(&c->btree_cache_freed);
INIT_LIST_HEAD(&c->data_buckets);
- iter_size = (sb->bucket_size / sb->block_size + 1) *
+ iter_size = ((meta_bucket_pages(sb) * PAGE_SECTORS) / sb->block_size + 1) *
sizeof(struct btree_iter_set);
c->devices = kcalloc(c->nr_uuids, sizeof(void *), GFP_KERNEL);