Win Server 2012 CPU throttling configuration tips

In the old version of Windows Server IIS already contains CPU throttling features, and there are also good examples, but as Microsoft's heavy launch of Windows Server 2012, it seems strict pursuit The high performance of the product, the function of IIS 8.0 has also been greatly improved. Where are the specific improvements reflected, let's take a look.

In older versions of IIS, the CPU usage was periodically checked by the polling mechanism, and if the usage exceeded the threshold for a long enough time, the corresponding action was taken. The problem with this approach is that CPU usage is not really limited. —— usage may be well above the configuration limit and remain high for a long enough period of time before the polling mechanism notices. If the CPU usage is found to exceed the threshold, the only available "corrective" action is to close the IIS worker process (W3pw.exe). For a period of time after the process is shut down, IIS also prevents the affected application from starting a new process, so the application pool does not recover immediately and continues to consume a lot of CPU resources. During this time, any requests to the application will fail, which will result in a very bad user experience.

In IIS 8.0, we worked with the Windows kernel team to improve the throttling mechanism for CPU usage. By replacing the old polling mechanism design, the kernel ensures that CPU usage is always below the specified level. With this change, we no longer need to close the W3Wp process of the over-application, so even if it is restricted, the application can remain active and continue to respond to user requests.

There are two new options for the CPU throttling mechanism in IIS 8.0. The Throttle configuration option ensures that CPU usage does not exceed the limit at all times. The ThrottleUnderLoad configuration option ensures that when CPU usage is high, CPU usage can not exceed the limit, but if the server is idle, it can consume more CPU resources. In this mode, once other processes require more CPU resources, the IIS worker process is limited to ensure that other processes can get the required resources.