经常听见有人说用Win7玩网络游戏的时候网络延时比较高，也就是ping比平时xp的时候高一点，一直找不到原因，很苦恼。今天我们终于找到理由了，原来是Win7的一个服务在作怪，这个服务叫：Multimedia Class Scheduler。
这个服务的官方解释是：
The Multimedia Class Scheduler service (MMCSS) enables multimedia applications to ensure that their time-sensitive processing receives prioritized access to CPU resources. This service enables multimedia applications to utilize as much of the CPU as possible without denying CPU resources to lower-priority applications.
MMCSS uses information stored in the registry to identify supported tasks and determine the relative priority of threads performing these tasks. Each thread that is performing work related to a particular task calls the AvSetMmMaxThreadCharacteristics or AvSetMmThreadCharacteristics function to inform MMCSS that it is working on that task.
For an example of a program that uses MMCSS, see Exclusive-Mode Streams
