title: Apache2 - Optimal values for ServerLimit, MaxClients, MaxRequestsPerChild for very HIGH traffic website
body: <p>I'm running a traffic intense site (100k daily). At peak time (1500+ active online) site gets drastically slowed down and increase in page loading time. ( images too )  </p>
  
  <p>We use front end + mysql database on same server. Have enough unutilized resources left.</p>
  
  <p>load average: 1.47, 1.63, 1.73
  htop: <a href="http://grabilla.com/02b13-02a8961d-bd7e-404c-9873-06e57bb7eab1.png" rel="nofollow">http://grabilla.com/02b13-02a8961d-bd7e-404c-9873-06e57bb7eab1.png</a></p>
  
  <p>Server config:
  E3 1230 (4 x 3.2Ghz) / 16GB RAM / 1Gbps Port Speed
  centoOS 5.8</p>
  
  <p>Apache config:</p>
  
  <pre><code>Timeout 150
  KeepAlive Off
  MaxKeepAliveRequests 1000
  KeepAliveTimeout 15
  
  &lt;IfModule prefork.c&gt;
  StartServers       8
  MinSpareServers    5
  MaxSpareServers   20
  ServerLimit      256
  MaxClients       256
  MaxRequestsPerChild  4000
  &lt;/IfModule&gt;
  
  &lt;IfModule worker.c&gt;
  StartServers         2
  MaxClients         450
  MinSpareThreads     25
  MaxSpareThreads     75 
  ThreadsPerChild     25
  MaxRequestsPerChild  0
  &lt;/IfModule&gt;
  </code></pre>
  
  <p>CPU usage never goes beyond 2 average load on peak hour. The MySQL server also has a 7~15% usage at that time. I know it's not a DB bottleneck because static pages also take long to load on peak hours.</p>
  
  <p>Any tips to optimize these values will be greatly appreciated, thanks.</p>
  
  <p>website url: <a href="http://goo.gl/XVPAA" rel="nofollow">http://goo.gl/XVPAA</a></p>