We upgraded Debian 9 (MariaDB 10.1.38) to Debian 10 (MariaDB 10.3.17). We experienced huge slowdowns (perhaps related to: https://jira.mariadb.org/browse/MDEV-16333)

We tried to speed up with these settings:

innodb_flush_method = O_DIRECT_NO_FSYNC
innodb_use_atomic_writes = 0
innodb_deadlock_detect = 0

But randomly it produces these errors:

2019-12-04 0:24:31 12111440 [ERROR] [FATAL] InnoDB: fsync() returned 5
191204 0:24:31 [ERROR] mysqld got signal 6 ;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.

To report this bug, see https://mariadb.com/kb/en/reporting-bugs

We will try our best to scrape up some info that will hopefully help
diagnose the problem, but since we have already crashed,
something is definitely wrong and this may fail.

Server version: 10.3.17-MariaDB-0+deb10u1-log