The goal of a Process is to serve as a unit of execution and allocation within a computing environment.
Virtual Machine abstraction provides a process with the illusion that it owns the entire machine, including CPU, Memory, and IO device multiplexing.
Process creation and switching are considered expensive due to the overhead involved in allocating resources and managing state.
The challenge associated with Threads is to decouple allocation and execution, allowing multiple threads to run within the same process.
The memory allocated to a process, which includes its code, data, stack, and heap segments.
The Thread Control Block (TCB) is a data structure that contains information about a thread, including its CPU registers, execution stack, and private state.
The Execution Stack is a structure that holds parameters, temporary variables, and return program counters while procedures are executing.
The shared state in a thread includes the content of memory such as global variables and heap, as well as I/O state like file system and network connections.
The private state of a thread is specific to that thread and is kept in the Thread Control Block (TCB), including CPU registers and the execution stack.
Multiprogramming is the ability to run multiple applications concurrently on a system.
Scheduling is less critical when threads operate on separate data, but it becomes important when threads share data, as it can affect the final values of shared variables.
The Execution Stack is a data structure that holds function arguments and return addresses, allowing for recursive execution and is crucial to modern programming languages.
A Ready Queue is a scheduler queue where threads that are not currently running are placed, waiting for CPU time.
In a multithreaded process, the Process Control Block (PCB) points to multiple Thread Control Blocks (TCBs), each representing a different thread within the process.
The Execution Stack is a data structure that holds function arguments, return addresses, and permits recursive execution, playing a crucial role in modern programming languages.
Start independent thread running given procedure.
The program would never print out the class list because the ComputePI function would never finish executing.
Switch overhead refers to the time and resources required to switch the CPU from one process to another, which is high due to the need to save and restore CPU state and manage memory/IO states.
Because the ComputePI function runs to completion before the PrintClassList function can execute, and if ComputePI does not finish, PrintClassList will not be called.
The thread creation overhead is low, meaning that creating new threads does not require significant resources.
It means ensuring that the total amount of money dispensed does not exceed the available balance in the account or the ATM's cash reserves.
The Deposit function illustrates how a thread can perform operations that may involve blocking I/O, such as retrieving and storing account information, while ensuring that the operations are completed in a controlled manner.
Function arguments are stored in the Execution Stack to provide the necessary data for function execution and to manage the flow of control during function calls.
It is called within the Timer Interrupt routine to switch execution to a new thread.
It addresses the issue of a user not inserting yield() calls, ensuring that threads can be preempted for better scheduling.
It represents the ordered execution of instructions in a program, which is crucial for process execution.
The Execution Stack is a data structure that stores information about the active subroutines of a computer program, including function calls, local variables, and control flow.
Protection for CPU is provided.
The dispatcher can regain control from a thread through internal events, where the thread returns control voluntarily, or through external events, where the thread gets preempted.
The possible values of x can vary based on the order of execution, with one possible outcome being x = 13.
When both threads access and modify the shared variable y, the final value of x can depend on the sequence of operations performed by each thread.
I/O Device Queues are separate queues for each device, signal, or condition, where threads wait for I/O operations to complete.
The Memory Footprint in a Two-Thread Example includes two sets of CPU registers and two sets of stacks, which are part of the program's address space.
The Stack Pointer is a register that points to the top of the current stack in memory, indicating where the next data can be pushed or popped.
The function run_new_thread() is used to initiate a new thread by selecting it and switching the context from the current thread to the new thread.
Switching threads across blocks requires changes to memory and I/O address tables, making it more complex than switching within a block.
The function A(int tmp) checks if tmp is less than 2; if true, it calls function B() and then prints the value of tmp.
The Execution Stack is a data structure that holds function arguments and return addresses, allowing for recursive execution and is crucial to modern programming languages.
The thread creation overhead is low.
The scheduling information stored in a TCB includes the thread's state, priority, and CPU time.
Recursive execution refers to the ability of a function to call itself, which is managed by the Execution Stack to keep track of multiple instances of the function.
Unbounded threads can lead to decreased throughput when a website becomes too popular, as the system may become overwhelmed with too many concurrent threads.
The OS keeps track of TCBs in protected memory, typically organized in an array or linked list.
The Stack Pointer is a register that points to the top of the current stack frame, helping to manage the stack's growth and access function arguments and return addresses.
It refers to a thread asking to wait for a signal from another thread, which results in yielding the CPU.
Ready Queues are scheduler queues where threads that are not currently running are placed, indicating that they are in a 'ready' state and waiting for CPU time.
The Dispatch Loop is the core of the operating system that continuously runs threads, chooses the next thread to execute, saves the state of the current thread control block (TCB), and loads the state of the new TCB in an infinite loop.
It behaves as if there are two separate CPUs, allowing concurrent execution of tasks.
To run a thread, you need to load its state (registers, stack pointer) into the CPU, load the environment (such as virtual memory space), and then jump to the program counter (PC).
Most of the time, threads work on separate data, making scheduling less critical. However, when threads share data, scheduling can lead to different outcomes based on the order of execution.
Most of the time, threads work on separate data, making scheduling less critical; however, when threads share data, scheduling can lead to different outcomes.
The ATM server problem involves servicing a set of requests while ensuring that the database remains uncorrupted and that excessive amounts of money are not dispensed.
Using one thread per request allows each request to proceed to completion while blocking as required, ensuring that operations like account deposits can be handled sequentially without interference.
The switch overhead in thread management is low, as it only involves saving and restoring the CPU state.
A multithreaded process is a process that contains multiple threads of execution, allowing for concurrent operations within the same process space.
The possible values of x can vary based on the execution order of the threads. For example, if Thread A executes first, x could be 5, depending on the value of y.
Concurrent threads are a useful abstraction that allows for the transparent overlapping of computation and I/O, as well as the use of parallel processing when available.
Corrupting the database can lead to inaccurate account balances, unauthorized transactions, and loss of trust in the banking system.
A scheduling method that uses timer interrupts to force scheduling decisions, allowing threads to be preempted for better scheduling.
The possible values of x can vary based on the order of execution of the threads, leading to different outcomes depending on how the threads are scheduled.
A potential issue with shared state in multithreading is that it can get corrupted when multiple threads access and modify the same data concurrently, leading to inconsistent results.
Recursive execution allows a function to call itself, which is facilitated by the Execution Stack maintaining separate instances of function arguments and return addresses.
The Execution Stack is a data structure that stores information about the active subroutines of a computer program, including local variables and return addresses.
Process creation overhead is the high cost associated with creating a new process, which involves allocating resources and initializing the process state.
The Execution Stack is a data structure that holds function arguments and return addresses, allowing for recursive execution and is crucial to modern programming languages.
Protection refers to the mechanisms in place to ensure that processes cannot interfere with each other's CPU and memory/IO states, ensuring system stability and security.
A Thread Control Block (TCB) is a data structure that contains information about a thread's execution state, scheduling information, various pointers for scheduling queues, and a pointer to the enclosing process (PCB).
Positioning stacks relative to each other involves ensuring that they do not overlap and are allocated in a way that optimizes memory usage and access speed.
The Execution Stack is crucial to modern programming languages as it enables function calls, recursion, and the management of execution flow.
The 'new' state indicates that the thread is being created.
An Interrupt Controller is a device that manages interrupt requests from various hardware devices, determining which request to honor based on priority and masking settings.
ThreadHouseKeeping() is responsible for deallocating finished threads to free up resources.
If threads violate stack size limits, it can lead to stack overflow, causing crashes or unpredictable behavior in the program.
The output of the execution stack example is 2.
Function C calls function A with the argument 2, which does not trigger the call to B() since 2 is not less than 2.
Violations of stack size limits can be caught using debugging tools, runtime checks, or by implementing guard pages that trigger exceptions when exceeded.
There is no protection for Memory/IO.
The 'waiting' state means the thread is waiting for some event to occur.
The function A(int tmp) checks if the input 'tmp' is less than 2; if true, it calls function B() and then prints the value of 'tmp'.
The working set is the subset of memory used by a process in a time window, and context switch time increases sharply with the size of the working set, potentially increasing by 100 times or more.
The server may become overwhelmed, leading to potential delays or failures in processing requests.
Recursive execution allows a function to call itself, which is managed by the Execution Stack to keep track of multiple instances of the function's parameters and return addresses.
Stack Growth refers to the dynamic increase in the size of the stack as new function calls are made, allowing for additional function arguments and return addresses to be stored.
Hyper-Threading is a technology that allows a single CPU core to act as two logical processors, enabling it to handle multiple threads simultaneously.
Cooperating threads enable the overlap of I/O operations and computation, allowing for better utilization of multiprocessors and the division of programs into parallel pieces for faster execution.
To perform periodic housekeeping tasks and to initiate the switching to a new thread.
Switching threads within a block is a simple thread switch that does not require significant changes to memory or I/O address tables.
The Execution Stack is a data structure that holds function arguments and return addresses, allowing for recursive execution and is crucial to modern programming languages.
During the switch operation, the program counter (PC), registers, and stack pointer of thread S are unloaded, and those of thread T are loaded, allowing thread T to resume execution.
The switch overhead is low, as it only involves the CPU state.
Stack Growth refers to the direction in which the stack expands in memory, typically growing downwards from higher to lower memory addresses.
The dispatcher saves the program counter (PC), registers, and stack pointer (SP) to prevent the next thread from overwriting them, ensuring isolation for each thread.
Recursive execution allows a function to call itself, which is managed by the Execution Stack to keep track of multiple function calls and their respective states.
A Thread Pool is a bounded collection of threads that are allocated to handle multiple tasks, preventing the creation of unbounded threads that can degrade performance when demand increases.
The Stack Pointer is a register that points to the top of the stack, indicating where the next function call's data will be stored.
Function B calls function C(), which in turn calls function A with a different argument, creating a chain of function calls.
The Mask in an Interrupt Controller enables or disables specific interrupts, allowing the system to control which interrupts can be processed.
Recursive execution refers to the ability of a function to call itself, which is managed by the Execution Stack to keep track of multiple instances of the function.
The function A checks if the input parameter tmp is less than 2; if true, it calls function B and then prints the value of tmp.
The Execution Stack is a data structure that stores information about the active subroutines of a computer program, including local variables, return addresses, and control flow.
When function C() is called, it invokes function A(2), which may lead to further recursive calls depending on the value of the argument.
The two types of stacks mentioned are the User Stack and the Kernel Stack, which are used to maintain the execution context of threads.
It can share file caches kept in memory and results of CGI scripts, and threads are cheaper to create than processes, resulting in lower per-request overhead.
The function A(int tmp) checks if the input 'tmp' is less than 2; if true, it calls function B() and then prints the value of 'tmp'.
Stack Growth refers to the direction in which the stack expands in memory, typically growing downwards from higher to lower memory addresses.
The queue in a Thread Pool is used to manage incoming connections, allowing threads to service requests in an organized manner and ensuring efficient use of resources.
The output is '2 1', as function A is called with 1, which leads to function B and then function C, which calls A with 2, printing 2 before returning to print 1.
A finished thread is moved to an 'exit/terminated' state and is not killed immediately; instead, it is managed by the ThreadHouseKeeping() function, which deallocates finished threads.
Concurrent threads can lead to issues such as programs being insensitive to arbitrary interleavings and shared variables becoming completely inconsistent without careful design.
The current status of input/output operations, including contexts for files and sockets.
The function A checks if the input 'tmp' is less than 2; if true, it calls function B and then prints the value of 'tmp'.
Sharing overhead is the high cost associated with sharing resources among processes, which typically involves at least one context switch.
The execution state of a TCB includes CPU registers, the program counter (PC), and a pointer to the stack (SP).
The BankServer process handles requests from an ATM network by continuously receiving and processing requests in a loop.
The Stack Pointer is a register that points to the top of the current stack frame, facilitating the management of function calls and local variables.
The while(TRUE) loop in proc B() signifies that the thread will run indefinitely, repeatedly yielding control to allow other threads to execute.
Recursive execution allows a function to call itself, which is facilitated by the Execution Stack managing multiple instances of function calls and their respective states.
Recursive execution refers to the ability of a function to call itself, which is managed by the Execution Stack to keep track of multiple instances of the function.
During the 'running' state, instructions are being executed.
The Deposit function retrieves the account using the account ID, updates the balance by adding the specified amount, and then stores the updated account information, which may involve disk I/O.
The Execution Stack is a data structure that holds function arguments and return addresses, allowing for recursive execution and is crucial to modern programming languages.
Stack Growth refers to the direction in which the stack expands in memory, typically growing downwards from higher to lower memory addresses.
One way to speed up processing is to handle more than one request at once by using multiple threads, allowing for concurrent processing of requests and overlapping computation with I/O operations.
The function A(int tmp) checks if tmp is less than 2; if true, it calls function B(), otherwise, it prints the value of tmp.
Function C calls function A with the argument 2, which does not trigger the call to B since 2 is not less than 2.
Thread switching is only slightly faster than process switching, with a time difference of about 100 nanoseconds.
Recursive execution refers to the ability of a function to call itself, which is supported by the Execution Stack through the management of multiple function calls and their respective states.
TCBs are organized into queues based on their state.
CPU scheduling is the process by which the operating system decides which thread to execute at any given time, optimizing CPU utilization and performance.
Switch overhead between hardware-threads refers to the minimal performance cost associated with switching execution between threads on a CPU, which is managed in hardware for efficiency.
The yield() function allows the current thread to voluntarily relinquish control of the CPU, enabling other threads to run.
The CPU provides protection in terms of CPU state, but not for memory and I/O.
The Execution Stack is a data structure that holds function arguments, return addresses, and permits recursive execution, playing a crucial role in modern programming languages.
The Execution Stack is a data structure that stores information about the active subroutines of a computer program, including local variables and return addresses.
The function A(int tmp) checks if tmp is less than 2, and if so, it calls function B() and then prints the value of tmp.
The current values of the program counter (PC), stack pointer (SP), and registers that define the execution state of a process.
The function A checks if the input 'tmp' is less than 2; if true, it calls function B, then prints the value of 'tmp'.
The Execution Stack is a data structure that stores information about the active subroutines of a computer program, including local variables and return addresses.
The Stack Pointer is a register that points to the top of the current stack frame, facilitating the management of function calls and local variables.
The Stack Pointer is a register that points to the top of the current stack in memory, indicating where the next data will be pushed or popped.
When function C() is called, it invokes function A(2), which may lead to further recursive calls depending on the value of the argument.
A server that uses multiple threads to handle incoming requests concurrently, allowing for efficient processing and resource sharing.
When function C() is called, it invokes function A(2), which is part of the recursive execution process managed by the Execution Stack.
The output of the execution stack example is 2, which is printed by function A when called with the argument 2.
A Non-Maskable Interrupt (NMI) is a type of interrupt that cannot be disabled by the CPU, ensuring that critical events are always processed.
The Execution Stack is a data structure that holds function arguments and return addresses, allowing for recursive execution and is crucial to modern programming languages.
The Stack Pointer is a register that points to the top of the current stack frame, facilitating the management of function calls and local variables.
The Stack Pointer is a register that points to the current top of the stack, indicating where the next function call's data will be stored.
The act of requesting I/O implicitly yields the CPU, allowing other threads to execute.
When function C() is called, it invokes function A(2), which is part of the recursive execution flow.
The output '2 1' signifies the order of execution and return values from the functions, where '2' is printed from the call to A(2) and '1' from A(1).
Context switching primarily depends on cache limits and the process or thread’s hunger for memory.
The computePI() function continuously computes digits and calls yield() to voluntarily give up the CPU, allowing other threads to run.
Different scheduler policies in I/O Device Queues allow for tailored management of how threads are scheduled based on the specific requirements of each device.
The function A(int tmp) checks if tmp is less than 2; if true, it calls function B() and then prints the value of tmp.
The sharing overhead is low, as the thread switch overhead is also low.
The proc A() function calls proc B(), which contains an infinite loop that continuously yields control back to the scheduler.
The Stack Pointer is a register that points to the top of the stack, indicating where the next function call's data will be stored.
The maximum size for stacks should be determined based on the expected depth of function calls and the overall memory constraints of the system.
The function A checks if the input 'tmp' is less than 2; if true, it calls function B and then prints the value of 'tmp'.
The 'ready' state signifies that the thread is waiting to run.
The ProcessRequest function executes the requested operation (like deposit) on the specified account using the provided account ID and amount.
kernel_yield is a trap to the operating system that allows the current thread to yield control, enabling the dispatcher to switch to another thread.
The Execution Stack is a data structure that holds function arguments, return addresses, and permits recursive execution, playing a crucial role in modern programming languages.
A context switch in Linux refers to the process of storing the state of a thread or process so that it can be resumed later, typically taking 3-4 microseconds on current Intel i7 and E5 processors.
The Stack Pointer is a register that points to the top of the current stack in memory, indicating where the next data can be pushed or popped.
The function A(int tmp) is a recursive function that calls function B() if the parameter tmp is less than 2, demonstrating how function calls are managed in the execution stack.
'ret=addrV' signifies the return address for function A when it is called with the argument 2, indicating where to return after execution.
A CPU can handle 4 threads at a time.
The function A(int tmp) checks if the input 'tmp' is less than 2, and if so, it calls function B() and then prints the value of 'tmp'.
The Interrupt Identity line specifies the identity of the interrupt, allowing the system to recognize which device has generated the interrupt request.
Switching across cores is about 2 times more expensive than switching within the same core.
The Stack Pointer is a register that points to the top of the current stack frame, facilitating the management of function calls and returns.
Kernel_yield refers to a trap to the operating system that allows the current thread to yield control and potentially switch to another thread.
A region of memory used for storing temporary data such as function parameters, return addresses, and local variables.
When function C() is called, it invokes function A(2), which may lead to further recursive calls depending on the value of 'tmp'.
A Priority Encoder selects the highest priority interrupt request that is currently enabled, ensuring that the most critical interrupts are handled first.
The OS is responsible for allocating and managing resources such as memory and I/O for processes.
Function B calls function C, which leads to another call to function A, creating a chain of function calls in the execution stack.
The sharing overhead is low, as the thread switch overhead is low.
The 'terminated' state indicates that the thread has finished execution.
The run_new_thread() function is responsible for selecting a new thread to run and switching the context from the current thread to the new thread.
The output of the provided execution stack example is 2, which is printed when the function A(2) is called.
The function A(int tmp) is a recursive function that calls function B() if the parameter tmp is less than 2, demonstrating how function calls are managed in the execution stack.
Recursive execution refers to the ability of a function to call itself, which is facilitated by the Execution Stack maintaining separate instances of function arguments and return addresses.
When function C() is called, it invokes function A(2), which may lead to further recursive calls depending on the value of 'tmp'.
The yield() function allows a thread to voluntarily give up the CPU, enabling other threads to execute.
Switching between User Stack and Kernel Stack is crucial for context switching, allowing the operating system to manage thread execution and resource allocation effectively.
The master() function allocates threads to handle incoming connections and manages a queue for these connections, continuously accepting new connections and waking up threads as needed.
The Execution Stack is a data structure that holds function arguments and return addresses, allowing for recursive execution and is crucial to modern programming languages.
When function A is called with an argument of 1, it checks if the argument is less than 2, calls function B, and then prints the argument.
The slave() function processes tasks by dequeuing connections from the queue and servicing web pages, sleeping if there are no connections to process.
Function B calls function C, which in turn calls function A with a new argument, demonstrating the flow of execution and the use of the Execution Stack.
The CPU can manage interrupts by using an internal flag to disable all interrupts, allowing it to perform critical tasks without interruption.
Active threads are represented by their Thread Control Blocks (TCBs).
Cooperating threads allow multiple users to share resources efficiently, such as one computer serving many users or multiple ATMs accessing a single bank balance, which enhances system functionality.
The Stack Pointer is a register that points to the top of the current stack frame, facilitating the management of function calls and local variables.
ThreadHouseKeeping() is responsible for deallocating finished threads and managing the resources associated with them.
Cooperating threads allow large problems to be broken down into simpler, manageable pieces, making systems easier to extend and maintain, as seen in the compilation process of gcc.
Contention for ALUs (Arithmetic Logic Units) and FPUs (Floating Point Units) occurs when multiple threads compete for access to these processing units, potentially degrading performance.
When function C() is called, it invokes function A(2), which may lead to further recursive calls depending on the value of 'tmp'.
Return addresses in the Execution Stack are used to determine where to return control after a function call is completed, ensuring proper execution flow.
With Hyper-Threading, a CPU can handle 8 threads at a time across its cores.
Recursive execution refers to the ability of a function to call itself, which is supported by the Execution Stack as it maintains separate stack frames for each function call.
Stack growth refers to the way the stack expands as new function calls are made, with each call pushing a new frame onto the stack, which includes local variables and return addresses.
Yield() must be called frequently enough to ensure that the CPU is shared effectively among threads.
