or download this
#!/usr/bin/perl
# Check the health of a mysql server.
...
print "The hit rate should be as close to 100% as possible. You can ca
+lculate your hit ratio by dividing the threads_created status variabl
+e by the Connections status variable:100 - ((Threads_created / Connec
+tions) * 100).If hitrate is very low like 1% then almost every mysql
+connection was causing a new thread to be created, and a lot of threa
+ds were being created, thus creating a lot of unnecessary overhead.Th
+e cause of the problem was that 'thread_cache_size' was set to 0. Thr
+ead_cache_size determines how many threads MySQL will hold open in me
+mory to handle new connections.To determine what you should set 'thre
+ad_cache_size' to, pay close attention to the 'threads_created' statu
+s variable. If it keeps going up it means your 'thread_cache_size' is
+ set too low. Just keep bumping up 'thread_cache_size' until 'threads
+_created' no longer increments.\n";
}