MySQL (Percona) 5.7 Upgrade - High CPU and Low RAM usage

[Mouth]

Yesterday I upgraded MySQL (Percona) from 5.6 to 5.7, using Percona's APT repository.
MySQLd was behaving fine prior, no issues, just upgrading for currency and any few features.

I have a 16Gb dedi, with InnoDB buffer pool given 8G. With MySQL 5.6 this was great, and mysqld sat around 20% CPU utilisation and approx 50% total memory utilisation.

Upgrade to MySQL 5.7, ensure same /etc/mysql/my.cnf config (upgrade didn't make changes) and ensure that 5.7 mysqld is using /etc/mysql/my.cnf still.

No, my mysqld is trashing CPU (400+ %) and memory usage is only 17% of total RAM.

Any thoughts?

 

[motowebmaster]

When I migrated to my current server, I set-aside my original custom cnf file and built a new one. Found that many of my old settings were conflicting with some mysql upgrades.

 

[Mouth]

When I migrated to my current server, I set-aside my original custom cnf file and built a new one. Found that many of my old settings were conflicting with some mysql upgrades.

Yeah good idea. I built one from https://tools.percona.com/wizard but that hasn't seemed to help.
You have 5.7? Care to share yours?

 

[Mouth]

Decided to rebuild all databases, in case the 5.6 -> 5.7 upgrade affected any indexes or table formats ...

user:/tmp# mysqldump -p --all-databases > dump.sql
user:/tmp# mysql -p < dump.sql

DB performance still the same (very poor) though.