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11 Cards in this Set
- Front
- Back
What resources are inherited acros
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-PID and parent PID
-real UID and parent GID -Session ID -Controlling Terminal -Time left until alarm signal. -Pending (blocked) signals. -cwd -root directory |
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Review the kernel startup process.
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1. BIOS begins executing, discovers devices, loads basic BIOS drivers, loads kernel into memory, transfers control to first instruction of kernel.
2. Kernel begins executing (possibly decompresses). 3. Kernel Initializes - memory is configured, interrupt vectors are set up. Device drivers initialized. Scheduling started. Printk("ag Burgers") from lab 1. Start kernel threads. Start the first process. |
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What is the name of the first process that is the parent of all other processes in UNIX?
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init.
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What are threads?
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Threads are multiple execution contexts within a single process.
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What resources are unique to a thread and what resources are shared between threads?
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Unique to a thread:
-CPU registers (general purpose, PC) -Stack -State Shared between threads: -Address space (global, static vars) -open files -child procs -signals,pending signals, signal handlers -accounting information |
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What are the benefits of threading?
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-Easy way to support concurrent users.
-Easier to create -Performace enhancement |
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What is the biggest benefit of threadsover processes?
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Synchronization overhead.
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What are two design patterns for working with threads?
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-Manager/worker
-Pipeline |
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What is a non-reentrant system call?
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A non-reentrant system call is one that cannot be called simultaneously from within the same process.
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Name two types of thread models.
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Kernel threads and user threads.
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What are the pros and cons of user threads?
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Pros:
-Smaller overhead -more control over scheduler -somewhat more portable Cons: -One blocking system call blocks entire process -Doesn't provide multi-core or multi CPU support -handling signals is difficult |