CPU overhead for trans_commit_stmt uses almost 2X more CPU in MyRocks than InnoDB #1486
Description
I am looking at flamegraphs from sysbench with a cached database and 1 client. A common problem I see is that the percentage of samples that lock_tables (and its callees) accounts for is ~2X larger in MyRocks than in InnoDB with simple microbenchmarks.
The microbenchmark in this case is here.
The percentage of samples from trans_commit_stmt and its children is 21.01% for InnoDB vs 35.19% for MyRocks
Percentage of samples, from InnoDB
21.01% trans_commit_stmt
17.97% MYSQL_BIN_LOG::commit
17.00% MYSQL_BIN_LOG::ordered_commit
3.60% MYSQL_BIN_LOG::flush_cache_to_file
3.05% MYSQL_BIN_LOG::process_commit_stage_queue
8.57% MYSQL_BIN_LOG::process_flush_stage_queue
1.27%. MYSQL_BIN_LOG::prepare
And from MyRocks
35.19% trans_commit_stmt
27.19% MYSQL_BIN_LOG::commit
26.19% MYSQL_BIN_LOG::ordered_commit
2.56% MYSQL_BIN_LOG::flush_cache_to_file
10.69% MYSQL_BIN_LOG::process_commit_stage_queue
... mostly RocksDB code
10.44% MYSQL_BIN_LOG::process_flush_stage_queue
... mostly RocksDB code
3.59% MYSQL_BIN_LOG::prepare
3.51% ha_prepare_low
3.32% myrocks::rocksdb_prepare
... more MyRocks and RocksDB code
2.20% is_thd_db_read_only_by_name
Flamegraphs
