Table of Contents
How are nested interrupts handled?
In a nested interrupt system, an interrupt is allowed to anytime and anywhere even an ISR is being executed. But, only the highest priority ISR will be executed immediately. The second highest priority ISR will be executed after the highest one is completed.
How stack is used in interrupt handling?
In contrast to the regular kernel stack that is allocated per process, the two additional stacks are allocated per CPU. Whenever a hardware interrupt occurs (or a softIRQ is processed), the kernel needs to switch to the appropriate stack. Historically, interrupt handlers did not receive their own stacks.
Do interrupts cause context switch?
A context switch can also occur as the result of an interrupt, such as when a task needs to access disk storage, freeing up CPU time for other tasks. Some operating systems also require a context switch to move between user mode and kernel mode tasks.
How interrupt requests from multiple devices can be handled?
Handling Multiple Devices: When more than one device raises an interrupt request signal, then additional information is needed to decide which device to be considered first. The following methods are used to decide which device to select: Polling, Vectored Interrupts, and Interrupt Nesting.
In a multitasking system, each thread of execution will typically have its own stack. If no special system stack is provided for interrupts, interrupts will consume stack space from whatever thread of execution is interrupted.
What is an interrupt and how are they handled?
An interrupt is a signal from a device attached to a computer or from a program within the computer that requires the operating system to stop and figure out what to do next. The computer simply takes turns managing the programs that the user starts.
How is a context switch initiated?
All context switches are initiated by an ‘interrupt’. This could be an actual hardware interrupt that runs a driver, (eg. from a network card, keyboard, memory-management or timer hardware), or a software call, (system call), that performs a hardware-interrupt-like call sequence to enter the OS.
How does a thread context switch work?
A typical thread context switch on a single-core CPU happens like this: All context switches are initiated by an ‘interrupt’.
How does the scheduler perform context switch?
Once both decisions have been made, the scheduler performs the context switch using the TCB of the current thread as well as that of the thread that is to be run next. A context switch itself consist of three main steps.
What is the TLB in context switch?
The TLB (Translation Lookaside Buffer), which is a cache containing recent virtual to physical address translations, is also flushed to prevent erroneous address translation. Note that this is the only step in the entire set of context switch actions that cares about processes!