Poor performance and crashing

I’ve got a virtual server with 256 RAM and 256 swap. I’ve ran load tests for this system but it seems, that over 100 users will bring mysql down. Could someone take a look at my my.cnf and tell if there’s something seriously wrong here.

I removed all comments to save space.

[client]port = 3306socket = /var/run/mysqld/mysqld.sock[mysqld]port = 3306socket = /var/run/mysqld/mysqld.sockskip-lockingkey_buffer = 128Mmax_allowed_packet = 1Mtable_cache = 256sort_buffer_size = 1Mread_buffer_size = 1Mread_rnd_buffer_size = 4Mmyisam_sort_buffer_size = 64Mthread_cache_size = 8query_cache_size= 16Mthread_concurrency = 8log-bin=mysql-binserver-id = 1[mysqldump]quickmax_allowed_packet = 16M[mysql]no-auto-rehash# Remove the next comment character if you are not familiar with SQL#safe-updates[isamchk]key_buffer = 128Msort_buffer_size = 128Mread_buffer = 2Mwrite_buffer = 2M[myisamchk]key_buffer = 128Msort_buffer_size = 128Mread_buffer = 2Mwrite_buffer = 2M[mysqlhotcopy]interactive-timeoutlog_slow_queries = /var/log/mysql/mysql-slow.loglong_query_time = 2

Key_buffer is a tad large if you also run a webserver. Aside from that, I can’t say much based on just your config. If you really got 128M of frequently used indices, you probably need a RAM upgrade.