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author | Coly Li <colyli@suse.de> | 2020-07-25 15:00:37 +0300 |
---|---|---|
committer | Jens Axboe <axboe@kernel.dk> | 2020-07-25 16:38:21 +0300 |
commit | 6907dc498f79543e5a32e632135e51b960331316 (patch) | |
tree | cf15002aca33b45d53abd8ee8939d05402849f6e /drivers | |
parent | 092bd54d69230b4a4a7f640a4cdcdeb004d3546e (diff) | |
download | linux-6907dc498f79543e5a32e632135e51b960331316.tar.xz |
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')
-rw-r--r-- | drivers/md/bcache/super.c | 2 |
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); |