RocksDBStore: add option to configure number of block cache shards

rocksdb_cache_size will be splitted into number of shards evenly.
More shards will reduce lock contentions.

Signed-off-by: Jianjian Huo <jianjian.huo@ssi.samsung.com>

diff --git a/src/common/config_opts.h b/src/common/config_opts.h
index f17d61f386f9e66bc3b7e1c2e2d35cbc095abc27..14cd0bb2b430c73d6071dbdaaa499ba36586bebd 100644 (file)
--- a/src/common/config_opts.h
+++ b/src/common/config_opts.h
@@ -842,7 +842,8 @@ OPTION(kinetic_use_ssl, OPT_BOOL, false) // whether to secure kinetic traffic wi
 OPTION(rocksdb_separate_wal_dir, OPT_BOOL, false) // use $path.wal for wal
 OPTION(rocksdb_db_paths, OPT_STR, "")   // path,size( path,size)*
 OPTION(rocksdb_log_to_ceph_log, OPT_BOOL, true)  // log to ceph log
-OPTION(rocksdb_cache_size, OPT_INT, 128*1024*1024)  // default leveldb cache size
+OPTION(rocksdb_cache_size, OPT_INT, 128*1024*1024)  // default rocksdb cache size
+OPTION(rocksdb_cache_shard_bits, OPT_INT, 4)  // rocksdb block cache shard bits, 4 bit -> 16 shards
 OPTION(rocksdb_block_size, OPT_INT, 4*1024)  // default rocksdb block size
 // rocksdb options that will be used for omap(if omap_backend is rocksdb)
 OPTION(filestore_rocksdb_options, OPT_STR, "")

diff --git a/src/kv/RocksDBStore.cc b/src/kv/RocksDBStore.cc
index d8be1fe5dc08d44aa328d4a3f6af5328b8cc1214..a9cb9f37d3e98c4ca8e180424910749a5983afad 100644 (file)
--- a/src/kv/RocksDBStore.cc
+++ b/src/kv/RocksDBStore.cc
@@ -279,13 +279,14 @@ int RocksDBStore::do_open(ostream &out, bool create_if_missing)
     opt.env = static_cast<rocksdb::Env*>(priv);
   }
 
-  auto cache = rocksdb::NewLRUCache(g_conf->rocksdb_cache_size);
+  auto cache = rocksdb::NewLRUCache(g_conf->rocksdb_cache_size, g_conf->rocksdb_cache_shard_bits);
   rocksdb::BlockBasedTableOptions bbt_opts;
   bbt_opts.block_size = g_conf->rocksdb_block_size;
   bbt_opts.block_cache = cache;
   opt.table_factory.reset(rocksdb::NewBlockBasedTableFactory(bbt_opts));
   dout(10) << __func__ << " set block size to " << g_conf->rocksdb_block_size
-           << " cache size to " << g_conf->rocksdb_cache_size << dendl;
+           << " cache size to " << g_conf->rocksdb_cache_size
+           << " num of cache shards to " << (1 << g_conf->rocksdb_cache_shard_bits) << dendl;
 
   opt.merge_operator.reset(new MergeOperatorRouter(*this));
   status = rocksdb::DB::Open(opt, path, &db);