The best MySQL Settings for 32GB RAM on a Dedicated Server

I am worrying about my memory usage as it is reaching more than 90% if I will not restart php-fpm.

I have the following configuration on my MySQL:

[client]
port            = 3306
socket          = /var/run/mysqld/mysqld.sock

[mysqld_safe]
socket          = /var/run/mysqld/mysqld.sock
nice            = 0

[mysqld]
user            = mysql
pid-file        = /var/run/mysqld/mysqld.pid
socket          = /var/run/mysqld/mysqld.sock
port            = 3306
basedir         = /usr
datadir         = /var/lib/mysql
tmpdir          = /tmp
lc-messages-dir = /usr/share/mysql
skip-external-locking

key_buffer              = 16M
max_allowed_packet      = 16M
thread_stack            = 192K
thread_cache_size       = 8

myisam-recover         = BACKUP
max_connections        = 250
table_cache            = 4K
wait_timeout            = 1200

query_cache_limit       = 1M
query_cache_size        = 128M
join_buffer_size        = 2M

log_error = /var/log/mysql/error.log

log_slow_queries        = /var/log/mysql/mysql-slow.log
long_query_time = 1

expire_logs_days        = 10
max_binlog_size         = 100M

innodb_buffer_pool_size = 5G
[mysqldump]
quick
quote-names
max_allowed_packet      = 16M

[isamchk]
key_buffer              = 16M

!includedir /etc/mysql/conf.d/

I am running nginx & php-fpm.

Two of my sites with lots of traffic are configured with this settings:

PHP-FPM pm.max_children: 64
PHP-FPM pm.start_servers: 20
PHP-FPM pm.min_spare_servers: 15
PHP-FPM pm.max_spare_servers: 64
PHP-FPM pm.max_requests: 500

The rest of my sites are configured using the following settings:

PHP-FPM pm.max_children: 64
PHP-FPM pm.start_servers: 10
PHP-FPM pm.min_spare_servers: 5
PHP-FPM pm.max_spare_servers: 15
PHP-FPM pm.max_requests: 500

When I restart mysql server and php-fpm, the initial size of memory consumed is 85%.
I created a script to monitor the consumption of the memory and if it reaches 90% I automatically restarted php-fpm. I don't know if this is a good idea

Configure some important variables in my.cnf file and restart MySQL service :

max_connections=500
max_connect_errors=100
innodb_buffer_pool_size={ value should be 70% of total Memory }
innodb_log_buffer_size={ less than 4 MB if there are TEXT/BLOB then set to more value between 8-128 MB }
innodb_file_per_table=ON
thread_cache_size={ if threads_connected value varies from 75 to 100, set thread_cache_size to 25 }
table_cache={ more than default }

StackExchange Database Administrators Q#50941, answer score: 2