| 摘要 |
The interprocess communications subsystem (IPC) of the microkernel, manages the message passing operations for the communication of control information and data between tasks. Every message sent from a sending task to a destination, receiving task must use the IPC subsystem to manage its transmission. The separation of transmission control information from the data portion of the message allows the performance of the message passing process to be linked to the relative complexity of the message to be transferred between two tasks. The transmission control information of a message is parsed only once and is copied, at most, only once in its sequential path from the sending task to the IPC subsystem, and then from the IPC subsystem to the destination task. If the message cannot be transmitted, for example because of processor resource exhaustion, a time out expiration, or insufficient port rights, then processor time is not wasted in the abortive transfer of the data portion of the message. In this manner, every message is required to interact with the IPC subsystem to bring order and predictability to interprocess communications in a busy, multitasking system, and yet the performance of the system is maximized. <MATH> |
