Microsoft® Windows Server™ 2003 White Paper
The main performance-related features are on the Performance Tab. This property page is used to configure the way that IIS handles processes. It is useful because you can tweak this behavior for each pool. This property page is shown below.
The Idle Timeout limit helps conserve system resources by terminating unused worker processes. IIS will gracefully shutdown an idle process after the time period elapses. The Request Queue Limit prevents a server from being overloaded by a large number of events. IIS monitors the number of requests for a designated application pool queue before adding a new request to the queue. Users receive a non-customizable 503 error response if the queue limit is exceeded.
CPU accounting allows you to keep a process from overloading a CPU. You can enable this and then set the percentage of processor usage the application can use. You can elect to take no action or terminate the pool when it exceeds this limit. An error is written to the Event Log when an exception occurs.
The last option affects Web gardens. A Web garden is an application pool using more than one worker process. A single Web garden may take advantage of multiple processors on a server. A Web garden can also establish affinity between processes and processors. Web gardens allow other processes to accept requests, even when one in the pool is unresponsive or hung.
The Web Garden option is critical to scale up scenarios. If you need to scale up, you can set up multiple Web gardens and control how many of them are running based upon your number of processors.
Implementing a Scalable Architecture19