[#MDEV-30335] Performance regression in 10.5.18

There seems to be some performance regression in 10.5.18 when compared to 10.5.9.
Customer noticed this while running mysqldump.
I ran sysbench test to verify this.
I used default configurations on both servers.
Below is the output and steps to reproduce.

Sysbench Prep
sysbench 1.0.20 (using bundled LuaJIT 2.1.0-beta2)

sysbench --db-driver=mysql --mysql-user=sbtest --mysql_password=Test@123 --mysql-db=test --mysql-host=192.168.20.14 --mysql-port=3306 /usr/share/sysbench/oltp_read_write.lua cleanup

sysbench --db-driver=mysql --mysql-user=sbtest --mysql_password=Test@123 --mysql-db=test --mysql-host=192.168.20.14 --mysql-port=3306 --table-size=1000000 /usr/share/sysbench/oltp_read_write.lua prepare

sysbench --db-driver=mysql --mysql-user=sbtest --mysql_password=Test@123 --mysql-db=test --mysql-host=192.168.20.21 --mysql-port=3306 /usr/share/sysbench/oltp_read_write.lua cleanup

sysbench --db-driver=mysql --mysql-user=sbtest --mysql_password=Test@123 --mysql-db=test --mysql-host=192.168.20.21 --mysql-port=3306 --table-size=1000000 /usr/share/sysbench/oltp_read_write.lua prepare

MariaDB 10.5.9
+-----------------------------+
\| VERSION() \|
+-----------------------------+
\| 10.5.9-6-MariaDB-enterprise \|
+-----------------------------+

sysbench --db-driver=mysql --mysql-user=sbtest --mysql_password=Test@123 --mysql-db=test --mysql-host=192.168.20.14 --mysql-port=3306 --threads=4 --time=60 --events=0 --report-interval=1 /usr/share/sysbench/oltp_read_write.lua run

SQL statistics:
queries performed:
read: 14196
write: 4054
other: 2027
total: 20277
transactions: 1013 (16.85 per sec.)
queries: 20277 (337.22 per sec.)
ignored errors: 1 (0.02 per sec.)
reconnects: 0 (0.00 per sec.)

General statistics:
total time: 60.1255s
total number of events: 1013

Latency (ms):
min: 117.25
avg: 237.05
max: 463.30
95th percentile: 308.84
sum: 240132.33

Threads fairness:
events (avg/stddev): 253.2500/6.22
execution time (avg/stddev): 60.0331/0.04

sysbench --db-driver=mysql --mysql-user=sbtest --mysql_password=Test@123 --mysql-db=test --mysql-host=192.168.20.14 --mysql-port=3306 --threads=4 --time=600 --events=0 /usr/share/sysbench/oltp_read_write.lua run

SQL statistics:
queries performed:
read: 138026
write: 39436
other: 19718
total: 197180
transactions: 9859 (16.43 per sec.)
queries: 197180 (328.53 per sec.)
ignored errors: 0 (0.00 per sec.)
reconnects: 0 (0.00 per sec.)

General statistics:
total time: 600.1856s
total number of events: 9859

Latency (ms):
min: 127.25
avg: 243.46
max: 652.59
95th percentile: 303.33
sum: 2400312.95

Threads fairness:
events (avg/stddev): 2464.7500/4.92
execution time (avg/stddev): 600.0782/0.04

MariaDB 10.5.18
+-------------------------------+
\| VERSION() \|
+-------------------------------+
\| 10.5.18-13-MariaDB-enterprise \|
+-------------------------------+
sysbench --db-driver=mysql --mysql-user=sbtest --mysql_password=Test@123 --mysql-db=test --mysql-host=192.168.20.21 --mysql-port=3306 --threads=4 --time=60 --events=0 --report-interval=1 /usr/share/sysbench/oltp_read_write.lua run

SQL statistics:
queries performed:
read: 13244
write: 3782
other: 1891
total: 18917
transactions: 945 (15.70 per sec.)
queries: 18917 (314.30 per sec.)
ignored errors: 1 (0.02 per sec.)
reconnects: 0 (0.00 per sec.)

General statistics:
total time: 60.1833s
total number of events: 945

Latency (ms):
min: 103.76
avg: 254.45
max: 548.79
95th percentile: 331.91
sum: 240451.74

Threads fairness:
events (avg/stddev): 236.2500/3.19
execution time (avg/stddev): 60.1129/0.04

sysbench --db-driver=mysql --mysql-user=sbtest --mysql_password=Test@123 --mysql-db=test --mysql-host=192.168.20.21 --mysql-port=3306 --threads=4 --time=600 --events=0 /usr/share/sysbench/oltp_read_write.lua run

SQL statistics:
queries performed:
read: 132664
write: 37904
other: 18952
total: 189520
transactions: 9476 (15.79 per sec.)
queries: 189520 (315.76 per sec.)
ignored errors: 0 (0.00 per sec.)
reconnects: 0 (0.00 per sec.)

General statistics:
total time: 600.1907s
total number of events: 9476

Latency (ms):
min: 142.03
avg: 253.30
max: 495.49
95th percentile: 320.17
sum: 2400233.10

Threads fairness:
events (avg/stddev): 2369.0000/5.61
execution time (avg/stddev): 600.0583/0.06

[MDEV-30335] Performance regression in 10.5.18 Created: 2023-01-04 Updated: 2023-10-12
Status:	Open
Project:	MariaDB Server
Component/s:	Server
Affects Version/s:	10.5.18
Fix Version/s:	10.5

[MDEV-30335] Performance regression in 10.5.18 Created: 2023-01-04 Updated: 2023-10-12