Commonly used server processors, such as Intel 486, Intel Pentium and Pentium Pro, and RISC processors, can handle thousands of interrupts and DPCs without being consumed by the task. However, each interrupt takes time away from the other work of the processor. An active server running Internet Information Server at high bandwidth can interrupt the processor enough to impede performance.
To help improve processor performance, some newer network card drivers provide an advanced feature known as interrupt moderation. When the driver detects a high rate of interrupts from the network adapter card, the interrupt moderation code disables interrupts and accumulates the interrupts in a buffer instead of sending them to the processor. When the processor has completed its work, the interrupts are reenabled.
Monitoring interrupts and DPCs is an important part of monitoring processor performance (and network adapter card performance) on a server running Internet Information Server. On a single processor system, a very high level of interrupts might indicate an errant network card or disk adapter, as well as an overworked processor. On a multiprocessor system, data about interrupts and DPCs might also reveal a poor distribution of workload among processors.