I have a lighttpd server which easily handles about 800 concurrent connections. But there seems to be a problem:
When the number of users grows, the CPU utilization grows as well, until a limit is reached at about 90%. The problem is when the number of the users drop down again... Even if I get back to around 300 to 400 users, the CPU is still at its peak and it seems to slow again as soon as more people come in again, say 500 to 600.
For example, right now I'm holding at 200 users but the CPU is still at 90% as if there were 900 people, when the server peaked...
What could be the cause of the problem? Might it be some configuration issue? RAM flushing? fastcgi? And how might I solve this problem? I really don't know what do, any advice?
Simply restarting the server is not an option as I would lose all connected users, and that's no good.
free -m results:
total used free shared buffers cached Mem: 1658 1365 292 0 123 1106 -/+ buffers/cache: 135 1522 Swap: 895 0 895