MySQL 5.7 comes with a new backup tool, named mysqlpump, which is almost the same as mysqldump with the ability of extracting data in parallel threads.
I tried a little experiment. Using a server containing 11 databases, with a total of 300 tables and about 20 million rows (roughly ≈ 10GB,) I used both mysqldump and mysqlpump to get a backup.
mysqldump --all-databases > dump.sql
mysqlpump --all-databases \
--add-drop-database --add-drop-table --skip-watch-progress \
--default-parallelism=10 \ …