MariaDB threads optimalization

mariadbperformancethreads

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

moved binary db files from

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.

Run mysqlslap benchmark (always restarted server before doing each test):

root@db1:/tmp # mysqlslap --user=root --query=/tmp/slap2.sql --create-schema=mydatabase --concurrency=1 --iterations=1
Benchmark
        Average number of seconds to run all queries: 59.573 seconds
        Minimum number of seconds to run all queries: 59.573 seconds
        Maximum number of seconds to run all queries: 59.573 seconds
        Number of clients running queries: 1
        Average number of queries per client: 100000


root@pcie:~# mysqlslap --user=root --query=/tmp/slap2.sql --create-schema=mydatabase --concurrency=1 --iterations=1
Benchmark
        Average number of seconds to run all queries: 31.151 seconds
        Minimum number of seconds to run all queries: 31.151 seconds
        Maximum number of seconds to run all queries: 31.151 seconds
        Number of clients running queries: 1
        Average number of queries per client: 100000
====================================================================================================================================
root@db1:/tmp # mysqlslap --user=root --query=/tmp/slap2.sql --create-schema=mydatabase --concurrency=100 --iterations=1
Benchmark
        Average number of seconds to run all queries: 568.082 seconds
        Minimum number of seconds to run all queries: 568.082 seconds
        Maximum number of seconds to run all queries: 568.082 seconds
        Number of clients running queries: 100
        Average number of queries per client: 100000

root@pcie:/etc/security/limits.d# mysqlslap --user=root --query=/tmp/slap2.sql --create-schema=mydatabase --concurrency=100 --iterations=1
Benchmark
        Average number of seconds to run all queries: 2059.712 seconds
        Minimum number of seconds to run all queries: 2059.712 seconds
        Maximum number of seconds to run all queries: 2059.712 seconds
        Number of clients running queries: 100
        Average number of queries per client: 100000



====================================================================================================================================
root@db1:/tmp # mysqlslap --user=root --query=/tmp/slap2.sql --create-schema=mydatabase --concurrency=8 --iterations=1
Benchmark
        Average number of seconds to run all queries: 134.003 seconds
        Minimum number of seconds to run all queries: 134.003 seconds
        Maximum number of seconds to run all queries: 134.003 seconds
        Number of clients running queries: 8
        Average number of queries per client: 100000

root@pcie:/etc/security/limits.d# mysqlslap --user=root --query=/tmp/slap2.sql --create-schema=mydatabase --concurrency=8 --iterations=1
Benchmark
        Average number of seconds to run all queries: 133.410 seconds
        Minimum number of seconds to run all queries: 133.410 seconds
        Maximum number of seconds to run all queries: 133.410 seconds
        Number of clients running queries: 8
        Average number of queries per client: 100000

As you can see, NEW (pcie) server is performing very good when running concurrency=1, performance is same when concurrency=8, and performance is very bad when concurrency=100.

Here are interesting results using internal benchmark:

root@pcie:~/slap/employees_db# mysqlslap --auto-generate-sql --concurrency=8 --iterations=500 --verbose
        Average number of seconds to run all queries: 0.002 seconds
DB1:    Average number of seconds to run all queries: 0.002 seconds

root@pcie:~/slap/employees_db# mysqlslap --auto-generate-sql --concurrency=16 --iterations=500
        Average number of seconds to run all queries: 0.007 seconds
DB1:    Average number of seconds to run all queries: 0.005 seconds

root@pcie:~/slap/employees_db# mysqlslap --auto-generate-sql --concurrency=32 --iterations=500
        Average number of seconds to run all queries: 0.015 seconds
DB1:    Average number of seconds to run all queries: 0.011 seconds

root@pcie:~/slap/employees_db# mysqlslap --auto-generate-sql --concurrency=64 --iterations=500
        Average number of seconds to run all queries: 0.033 seconds
DB1:    Average number of seconds to run all queries: 0.029 seconds

root@pcie:~/slap/employees_db# mysqlslap --auto-generate-sql --concurrency=128 --iterations=500
        Average number of seconds to run all queries: 0.074 seconds
DB1:    Average number of seconds to run all queries: 0.097 seconds

root@pcie:~/slap/employees_db# mysqlslap --auto-generate-sql --concurrency=256 --iterations=500
        Average number of seconds to run all queries: 0.197 seconds
DB1:    Average number of seconds to run all queries: 0.293 seconds

root@pcie:~/slap/employees_db# mysqlslap --auto-generate-sql --concurrency=512 --iterations=500
        Average number of seconds to run all queries: 0.587 seconds
DB1:    Average number of seconds to run all queries: 1.009 seconds

Internal mysqlsap benchmark is too synthetic, so I load employees db:
https://launchpad.net/test-db/employees-db-1/1.0.6/+download/employees_db-full-1.0.6.tar.bz2

SQL:

#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;

Results:

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)

with 512 concurrency, QUERY CACHE disabled: 

OLD db1 server:  Average number of seconds to run all queries: 72.710s
NEW PCIE server: Average number of seconds to run all queries: 29.774s

Anybody have idea what to check, how to optimize the setup? I am using MyISAM tables only in my DB, mariadb config is same on both servers…

Update with more info: Initially I installed on NEW DB server FREEBSD, MariaDB performance was bad, I thought it is OS related problem, but same symptoms are on Linux. During benchmark there is basically no IO after filling the cache, so this is not IO related problem.

Thanks for any ideas.

Best Answer

I am going to answer my own question. I spent couple of days solving this problem. Problem was NUMA. But let's peek into this more.

For understanding the problem we need CPU information:

# lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                16
On-line CPU(s) list:   0-15
Thread(s) per core:    2
Core(s) per socket:    4
Socket(s):             2
NUMA node(s):          2
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 79
Model name:            Intel(R) Xeon(R) CPU E5-2637 v4 @ 3.50GHz
Stepping:              1
CPU MHz:               1262.725
CPU max MHz:           3500.0000
CPU min MHz:           1200.0000
BogoMIPS:              6999.47
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              15360K
NUMA node0 CPU(s):     0-3,8-11
NUMA node1 CPU(s):     4-7,12-15
Flags:                 fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch epb invpcid_single intel_pt tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm cqm rdseed adx smap xsaveopt cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local dtherm arat pln pts

Important is NUMA node(s): 2. The server got TWO CPUs, on TWO nodes. Read more about NUMA, read more about NUMA and mysql based databases.

To speed up the queries we need to run MariaDB using numactl. I made some benchmarks, and the best setting was

numactl --cpunodebind=1 --membind=1  /usr/sbin/mysqld

Overall the Query Cache is not scaling well on multiple threads, so some DBA suggest to turn it off.

Benchmark results (QC is Query Cache), MyISAM tables, concurrency 64 on my database using mysqlslap, simplified output, lower is better:

QC-ON  | numactl --cpunodebind=1 --membind=1   | 16.311s
QC-OFF | numactl --cpunodebind=1 --membind=1   | 17.575s 
QC-ON  | [standard execution]                  | 27.177s
QC-OFF | [standard execution]                  | 29.850s
QC-ON  | numactl --interleave all              | 28.664s
QC-OFF | numactl --interleave all              | 30.071s
QC-ON  | numactl -N=1 -m=1 noibrs noibpb nopti | 15.976s

According to these results the best is specify "numactl --cpunodebind=1 --membind=1" and still have Query Cache turned on. I tried kernel with noibrs noibpb nopti flags, speed gain is quite low, only 2%. What surprised me is bad results with numactl --interleave all

So, if you experience strange slow results on new more powerful server, be sure you understand NUMA, it can save a lot of time for debugging.

Script to run benchmark:

#!/bin/bash
COUNTER=1
while [ $COUNTER -le 512 ]; do
    mysqlslap --pre-query="RESET QUERY CACHE;" --create-schema=mydatabase --query="/tmp/slap3.sql" --iterations=10 --concurrency=$COUNTER --csv
    let COUNTER=COUNTER*2
done
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