| Message ID | 20200715143015.14957-16-colyli@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | bcache: extend bucket size to 32bit width | expand |
On 7/15/20 4:30 PM, colyli@suse.de wrote: > From: Coly Li <colyli@suse.de> > > 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> > --- > drivers/md/bcache/super.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c > index e0da52f8e8c9..90494c7dead8 100644 > --- a/drivers/md/bcache/super.c > +++ b/drivers/md/bcache/super.c > @@ -1908,7 +1908,7 @@ 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); > Reviewed-by: Hannes Reinecke <hare@suse.de> Cheers, Hannes
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index e0da52f8e8c9..90494c7dead8 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -1908,7 +1908,7 @@ 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);