Hi All, I got problem with mariadb performance, NEW (pcie) server: Intel(R) Xeon(R) CPU E5-2637 v4 @ 3.50GHz, 1TB NVMe disks, 128 GB RAM, installed Debian 4.9.65-3+deb9u1, Ver 15.1 Distrib 10.1.26-MariaDB OLD server: Intel(R) Xeon(R) CPU E5-1630 v3 @ 3.70GHz, SSD disk, 64 GB RAM, FreeBSD 11.0-STABLE, 10.1.21-MariaDB On servers is running just mysql, I copy my.ini file, config files are same. mysql slap results for example employees db: #less /root/slap/select_query.sql SELECT emp_no, first_name, last_name, gender FROM employees LIMIT 10; SELECT emp_no, first_name, last_name, gender FROM employees ORDER BY last_name ASC LIMIT 10; SELECT COUNT(emp_no) FROM employees WHERE last_name = 'Aamodt'; SELECT last_name, COUNT(emp_no) AS num_emp FROM employees GROUP BY last_name ORDER BY num_emp DESC LIMIT 10; SELECT employees.* FROM employees LEFT JOIN dept_emp ON ( dept_emp.emp_no = employees.emp_no ) LEFT JOIN salaries ON ( salaries.emp_no = salaries.emp_no ) WHERE employees.first_name LIKE '%Jo%' AND salaries.from_date > '1993-01-21' AND salaries.to_date < '1998-01-01' LIMIT 0, 100; root@pcie:~/slap# mysqlslap --pre-query="RESET QUERY CACHE;" --create-schema=employees --query="/root/slap/select_query.sql" --iterations=10 --concurrency=1 Average number of seconds to run all queries: 0.459 seconds DB1: Average number of seconds to run all queries: 0.627 seconds root@pcie:~/slap# mysqlslap --pre-query="RESET QUERY CACHE;" --create-schema=employees --query="/root/slap/select_query.sql" --iterations=10 --concurrency=2 Benchmark Average number of seconds to run all queries: 0.473 seconds DB1: Average number of seconds to run all queries: 0.626 seconds root@pcie:~/slap# mysqlslap --pre-query="RESET QUERY CACHE;" --create-schema=employees --query="/root/slap/select_query.sql" --iterations=10 --concurrency=4 Average number of seconds to run all queries: 0.486 seconds DB1: Average number of seconds to run all queries: 0.656 seconds root@pcie:~/slap# mysqlslap --pre-query="RESET QUERY CACHE;" --create-schema=employees --query="/root/slap/select_query.sql" --iterations=10 --concurrency=8 Average number of seconds to run all queries: 0.569 seconds DB1: Average number of seconds to run all queries: 1.136 seconds root@pcie:~/slap# mysqlslap --pre-query="RESET QUERY CACHE;" --create-schema=employees --query="/root/slap/select_query.sql" --iterations=10 --concurrency=16 Benchmark Average number of seconds to run all queries: 0.948 seconds DB1: Average number of seconds to run all queries: 1.750 seconds root@pcie:~/slap# mysqlslap --pre-query="RESET QUERY CACHE;" --create-schema=employees --query="/root/slap/select_query.sql" --iterations=10 --concurrency=32 Average number of seconds to run all queries: 1.650 seconds DB1: Average number of seconds to run all queries: 2.455 seconds root@pcie:~/slap# mysqlslap --pre-query="RESET QUERY CACHE;" --create-schema=employees --query="/root/slap/select_query.sql" --iterations=10 --concurrency=64 Average number of seconds to run all queries: 3.306 seconds DB1: Average number of seconds to run all queries: 3.176 seconds root@pcie:~/slap# mysqlslap --pre-query="RESET QUERY CACHE;" --create-schema=employees --query="/root/slap/select_query.sql" --iterations=10 --concurrency=128 Average number of seconds to run all queries: 6.744 seconds DB1: Average number of seconds to run all queries: 5.737 seconds root@pcie:~/slap# mysqlslap --pre-query="RESET QUERY CACHE;" --create-schema=employees --query="/root/slap/select_query.sql" --iterations=10 --concurrency=256 Average number of seconds to run all queries: 13.474 seconds (verified 2nd run: 12.883 seconds) DB1: Average number of seconds to run all queries: 3.451 seconds (verified 2nd run: 4.935 seconds) root@pcie:~/slap# mysqlslap --pre-query="RESET QUERY CACHE;" --create-schema=employees --query="/root/slap/select_query.sql" --iterations=10 --concurrency=512 Average number of seconds to run all queries: 26.085 seconds (verified 2nd run: 26.307 seconds) DB1: Average number of seconds to run all queries: 15.862 seconds (verified 2nd run: 11.280 seconds) as you can see with raising threads PCIE performance is lowering rapidly. Any idea what to check? Thank you. I post this question couple of days with more information also here: https://serverfault.com/questions/895506/mariadb-threads-optimalization