All tests were processed in Amazon EC2 c3.2xlarge (vCPU 8, 15 Gb RAM) instance with additional SSD disk (500 Gb, 4000 iOPS) for storing databases (Mongo, MySQL).

MongoDB 2.6 vs MongoDB 3.0 MMAPv1

15 parallel updates in MongoDB 2.6 and MongoDB 3.0 MMAPv1

30 parallel updates in MongoDB 2.6 and MongoDB 3.0 MMAPv1

MongoDB 3.0 MMAPv1 vs MongoDB 3.0 WiredTiger

15 parallel updates in MongoDB 3.0 MMAPv1 and MongoDB 3.0 WiredTiger

30 parallel updates in MongoDB 3.0 MMAPv1 and MongoDB 3.0 WiredTiger

MongoDB 3.0 WiredTiger vs MySQL 5.5 InnoDB

The settings below were added into MySQL config before running tests:

max_connections = 10000

query_cache_limit = 32M
query_cache_size = 1024M

innodb_buffer_pool_size = 8192M
innodb_log_file_size = 512M
innodb_thread_concurrency = 16
innodb_flush_log_at_trx_commit = 2

thread_cache = 32
thread_cache_size = 16

15 parallel updates in MongoDB 3.0 WiredTiger and MySQL 5.5 InnoDB

30 parallel updates in MongoDB 3.0 WiredTiger and MySQL 5.5 InnoDB

You could find some additional information in article in my personal blog or in article in my habrahabr blog (rus)