After all these years I'm still learning that Apache's own configuration can dramatically effect server performance. In this case, more so than the MySQL configuration.

KeepAliveTimeout on my server was set to 8 seconds. Since I have this signature script doing 1,750,000+ impressions a day, I had a boatload of connections in "waiting" mode - 256 of them in fact. 256 * 8MB httpd process is 2GB itself with no room for MySQL to run.

I lowered by KeepAliveTimeout to 2 and it had a dramatic effect on my server performance. I'm lowered the number of servers than can run down to 180 to fit within my membery limits and also considering dropping my timeout limit to 1.

Since doing this I've seen a dramatic reduction in the use of memory by Apache processes and a boot in site performace (pages taking 2.5 seconds to process are now taking half that time).

So, while tuning MySQL, you will probably want to look at your Apache configuration, too.

It's a system. It all has to work well together as a unit.

I didn't want to muddy the waters in in your persistant = bad thread because in most cases that is true, but as you get your system's parts more into tune with each other it doesn't HAVE to be bad. You've dramatically reduced the number of apache proceses. If you go back and balance that number with the number of MySQL connections allowed, and balance all of that to the amount of memory you have to use you might find they work ok for you.

As an aside, look at your apache. Have you compiled your modules in or are they loading as a DSO? Are you loading modules that you don't need? Memory waster there if you are. @8megs per my guess is you're not loading a lot of unused modules, but it's worth checking. A meg here, a meg there......

[]PhotoPost said:I lowered by KeepAliveTimeout to 2 and it had a dramatic effect on my server performance.... and also considering dropping my timeout limit to 1.[/]

Just disable KeepAlive:
http://www.slogic.org/manual/ibm/9atperf.htm