how to reduce mysql overhead? My machine has 2GB RAM, I have some cron job run every minute insert into some data. 

My mysql always overhead. I think it is very frequently, if some cron job mysql insert run, 5-10 minutes, the db will become overhead. 12 hours later, the overhead data will increase into 1-2MB.

how to reduce mysql overhead? this is my my.cnf

key_buffer_size = 256M
key_buffer = 128M
back_log = 3000
max_allowed_packet = 4M
table_cache = 2048
table_open_cache = 512
sort_buffer_size = 8M
read_buffer_size = 2M
read_rnd_buffer_size = 4M
bulk_insert_buffer_size = 256M
myisam_sort_buffer_size = 128M
thread_cache_size = 8
thread_cache = 512
query_cache_size = 384M
set-variable =wait_timeout=60
thread_concurrency = 4
log-slow-queries = slow.log
long_query_time = 1
innodb_flush_log_at_trx_commit = 2
innodb_buffer_pool_size = 384M
ft_min_word_len=3
# log-bin=mysql-bin


here is some print in phpmyadmin.

Table    Action  Records  Type    Collation    Size       Overhead
table_nam        101,399  MyISAM  utf8_unicode_ci  112.7 MiB  1.2 MiB
You use mytop and mysqltuner to analyze using mysql resources (RAM and CPU).

Too enable the option to log slow queries:

log_slow_queries = /var/log/mysql/mysql-slow.log
long_query_time = 3


And check out this post about ntpd service:

https://stackoverflow.com/questions/1282232/mysql-high-cpu-usage

I have a dedicated server for a high rate of transactions:

max_allowed_packet=16M
key_buffer_size=8M
innodb_additional_mem_pool_size=10M
innodb_buffer_pool_size=512M
join_buffer_size=40M
table_open_cache=1024
query_cache_size=40M
table_definition_cache=256
innodb_additional_mem_pool_size=10M
key_buffer_size=16M
max_allowed_packet=32M
max_connections = 300
query_cache_limit = 10M
log_slow_queries = /var/log/mysql/mysql-slow.log
long_query_time = 3


Regards.