kernelDesignSept28

kernelDesignSept28 - 10/27/11 1 RTS: Kernel Design 10/27/11...

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Unformatted text preview: 10/27/11 1 RTS: Kernel Design 10/27/11 2 Kernel & Device drivers Shell XWin Thread lib ftp User applications System call interface Devices Process, memory, file system, network managers. Device drivers Kernel Servers (application ~, web ~, component ~) Hardware/controller 10/27/11 3 Simple kernels Polled loop: Say a kernel needs to process packets that are transferred into the DMA and a flag is set after transfer: for(;;) { if (packet_here) { process_data(); packet_here=0; } } Excellent for handling high-speed data channels, a processor is dedicated to handling the data channel. Disadvantage: cannot handle bursts 10/27/11 4 Simple kernels: cyclic executives Illusion of simultaneity by taking advantage of relatively short processes in a continuous loop: for(;;) { process_1(); process_2(); process_3(); process_n(); } Different rate structures can be achieved by repeating tasks in the list: for(;;) { process_1(); process_2(); process_3(); process_3(); } 10/27/11 5 Cyclic Executives: example: Interactive games Space invaders: for(;;) { check_for_keypressed(); move_aliens(); check_for_keypressed(); check_collision(); check_for_keypressed(); update_screen(); } } check_keypressed() checks for three button pressings: move tank...
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This document was uploaded on 10/27/2011 for the course CSE 321 at SUNY Buffalo.

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kernelDesignSept28 - 10/27/11 1 RTS: Kernel Design 10/27/11...

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