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Functions of Operating Systems

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Firm Timer Implementation – Georgia Tech – Advanced Operating Systems

Firm Timer Implementation – Georgia Tech – Advanced Operating Systems

As you know, in Linux they use the term task to signify a schedulable entity. And so, we’re using T1, T2, T3, to mean tasks, which are schedulable entities. And the timer-q data structure, what it contains is the tasks and the expiry time for that particular task. And the tasks are ordered in this […]

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Summarizing Scheduling Policies – Georgia Tech – Advanced Operating Systems

Summarizing Scheduling Policies – Georgia Tech – Advanced Operating Systems

So to summarize the scheduling policies, I already mentioned that first come first serve simply ignores affinity, and pays attention only to fairness. And these next two policies that I introduced to you, fixed processor and last processor, the focus is on cache affinity of a thread with respect to a particular processor. That’s what […]

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Object Invocation Across the Network – Georgia Tech – Advanced Operating Systems

Object Invocation Across the Network – Georgia Tech – Advanced Operating Systems

As I mentioned, Spring is a network operating system. So, what I described to you just now, is how object invocation works within a single node. But these doors are confined to the nucleus on a single node. And we need to be able to do object invocation across the network. The client domain may […]

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Control Transfer – Georgia Tech – Advanced Operating Systems

Control Transfer – Georgia Tech – Advanced Operating Systems

So control transfer in a fully virtualized setting happens implicitly from the guest to the hypervisor. How? When the guest operating system executes any privileged instruction. Because it thinks it can do it, it’ll result in a trap and hypervisor will catch it. And then do the appropriate thing. That’s how control is transferred from […]

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Algorithm Grading Quiz Solution – Georgia Tech – Advanced Operating Systems

Algorithm Grading Quiz Solution – Georgia Tech – Advanced Operating Systems

So I’m going to give you the solution for this particular question by filling out this table. And as I said, take your time thinking about it. And, and verifying your own intuition against what I’m presenting to you here. Now what you’ll find is that MCS Link-based queue lock and Anderson’s array-based queue lock […]

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IPC Fundamental to System Services – Georgia Tech – Advanced Operating Systems

IPC Fundamental to System Services – Georgia Tech – Advanced Operating Systems

Because Quicksilver is a distributed operating system, IPC both within, and on the local data network is a crucial component of Quicksilver. And this picture shows the semantics of the IPC call. In the kernel, there is a data structure called service queue. Which is created by the server that wants the service, request from […]

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Graceful Degradation – Georgia Tech – Advanced Operating Systems

Graceful Degradation – Georgia Tech – Advanced Operating Systems

And the DQ principle is also very useful for managing graceful degradation of service. So DQ defines to total system capacity. So if a server is saturated, meaning that we have reached the limit of the server in terms of DQ. That’s a constant. DQ’s a constant. And so if you reach that limit, then […]

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Efficient Mapping (Full Virtualization) – Georgia Tech – Advanced Operating Systems

Efficient Mapping (Full Virtualization) – Georgia Tech – Advanced Operating Systems

As I mentioned in a fully virtualized setting, the guest operating system has no idea about machine pages. It thinks that the physical page number that it is generating, is the real thing. But it is not. And therefore, there is two levels of indirection, one level of indirection going from virtual page to physical […]

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Mouse Click Quiz Solution – Georgia Tech – Advanced Operating Systems

Mouse Click Quiz Solution – Georgia Tech – Advanced Operating Systems

As you may have guessed, the right choice is, the most clicked results in a CPU interrupt. That’s the first thing that happens, and once the interrupt has been delivered to the CPU, there are domino effects that may eventually result in some program running to read the spacial coordinates. But the thing that happens […]

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Large Protection Domains – Georgia Tech – Advanced Operating Systems

Large Protection Domains – Georgia Tech – Advanced Operating Systems

You may ask, what if the protection domain is so large that it needs all of the hardware address space? Maybe the file system code base is so big that it needs the entire hardware address space. Cannot share it with anybody else. Similarly, the code base for the storage module is so big that […]

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