Embedded Operating Systems. EE138 – SJSU Christopher Pham. Objectives. Define operating system Discuss process management, scheduling, and inter-task communication Introduce memory management at the OS level Discuss I/O management in operating systems . Overview.
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EE138 – SJSU
The kernel is a component that contains the main functionality of the OS, specifically all or some combination of features and their inter- dependencies, including:
The advantages of the fork/exec model, however, include the efficiency gained by the child task inheriting properties from the par- ent task, and then having the flexibility to change the child task’s environment afterwards.
Under the spawn approach, there are no duplicate memory spaces to be created and destroyed, and then new space allocated, as is the case with the fork/exec model.
More reading: vxWork real world example
embedded OSes provide different mechanisms that allow for tasks in a multitasking system to intercommunicate and synchronize their behavior so as to coordinate their functions, avoid problems, and allow tasks to run simultaneously in harmony.
Note: Thrashing: a situation when a system’s resources are drained by the OS constantly swapping inand out data from memory. To avoid thrashing, a kernel may implement a working set model, which keeps a fixed number of pages of a process in memory at all times.
Virtual memory is typically implemented via
When virtual memory is implemented via these “demand” techniques, it means that only the pages and/or segments that are currently in use are loaded into RAM.