In windows server 2012 with 2 CPUs I have apache 2.4 with PHP 5.6 and when I put a load on the web server a cumulative 50% of total CPU power is used. No matter what I do, I cannot get the total over 50%.

Each individual CPU will be less than 50% and if one spikes up the other spikes down at the same time. It seems like windows is limiting the Apache service to use 50% of the CPU.

UPDATE: If I keep the Apache server loaded for longer than 60 seconds, once it hits 60 seconds the CPU utilization goes to 100%. It is like there is a 60 second timer that kicks it up to 100%. It really seems like a windows server setting, or could it be a VMware setting?

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    Is hyperthreading enabled at a BIOS level? Also how is CPU usage being monitored? – Matt Jul 9 '15 at 20:53
  • This is a VM, I am not sure about the BIOS... I am just using windows performance monitor. Notice I updated my post to say that after 60 seconds of load, the usage kicks up to 100%, making me think it must be some environment configuration... – Roofus McDuffle Jul 9 '15 at 21:26
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    Given that it is a VM it is possible that the hypervisor is potentially withholding some resources, 1/2 dedicated cores e.g. until certain resource consumption thresholds are met. The timer/resource management may be accessible/configurable through the hypervisor's management interface. – Matt Jul 9 '15 at 21:31
  • Thank you. I just discovered the 60 second timer thing. I will look into this more. When I blast it with prime95 both cores immediately spike to 100% but maybe there is a difference in the way it doles out resources for different processes (httpd is running as a service). – Roofus McDuffle Jul 9 '15 at 21:37

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