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?