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Unformatted text preview: COP4600 17-5-10 Operating System Structures Microkernel Mach an early example of a microkernel OS; it's been used to host an emulator for other OSen (e.g., UNIX). user-space user prog user prog user prog UNIX emulator minimal kernel memory process terminal low-level comm management management driver software disk drivers network drivers hardware- user programs use API's of the UNIX emulator- UNIX emulator uses API of MM and PM- MM interacts with disk drivers- LLCS interacts with the network drivers- drivers interact with the hardware Why microkernel OS? (take 2) * services that run above the kernel are easier to engineer, update, tune, & maintain * the kernel is responsible for providing efficient basic mechanisms * user-level servers flexibly implement system policies- can enable programmers to (more easily) control priorities Why not microkernel OS? * performance has (traditionally) been an issue- a given service may respond more slowly when implemented at the user level Other examples of Client-Server architectures Windows NT Win32 Win32 OS/2 OS/2 POSIX POSIX App ServerApp ServerApp Server ^ ^ ^ \...
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- Spring '08