请教军哥my.cnf参数调整

gdwest

我的服务器是8核16g的CentOS 6.9 64位，平时内存使用率只有20%不到那样，我想着调高my的配置，提高内存利用率和性能，my.cnf我调整具体为下面这样，请问有哪一个参数过大或者过小吗？谢谢
skip-external-locking
key_buffer_size = 128M
max_allowed_packet = 16M
table_open_cache = 2048
sort_buffer_size = 8M
net_buffer_length = 8K
read_buffer_size = 8M
read_rnd_buffer_size = 8M
myisam_sort_buffer_size = 32M
thread_cache_size = 128
query_cache_size = 128M
tmp_table_size = 2048M

group_concat_max_len = 10240000000

#skip-networking
max_connections = 500
max_connect_errors = 100
open_files_limit = 65535

#log-bin=mysql-bin
#binlog_format=mixed
server-id        = 1
expire_logs_days = 10

default_storage_engine = InnoDB
innodb_file_per_table = 1
innodb_data_home_dir = /usr/local/mysql/var
innodb_data_file_path = ibdata1:10M:autoextend
innodb_log_group_home_dir = /usr/local/mysql/var
innodb_buffer_pool_size = 8000M
innodb_additional_mem_pool_size = 128M
innodb_log_file_size = 128M
innodb_log_buffer_size = 8M
innodb_flush_log_at_trx_commit = 1
innodb_lock_wait_timeout = 50

[mysqldump]
quick
max_allowed_packet = 16M

[mysql]
no-auto-rehash

[myisamchk]
key_buffer_size = 128M
sort_buffer_size = 8M
read_buffer = 2M
write_buffer = 2M

[mysqlhotcopy]
interactive-timeout