Virtual Memory and Memory Pages Quiz

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What happens when the main memory is full in iOS?

The system automatically reboots.

No impact on the system.

Virtual memory is disabled.

Processes are terminated until there is enough free memory. (correct)

Why does Android not write memory pages back to flash storage on mobile devices?

It improves system performance significantly.

It drains the battery and shortens flash storage lifespan. (correct)

It speeds up disk access.

It helps in reducing virtual memory.

What occurs when a process needs to use memory in a memory page that triggers a page fault?

The memory page is mapped to a vacant memory frame. (correct)

The process terminates immediately.

The memory page is stored in flash storage.

The system crashes.

Why do virtual memory addresses differ from physical addresses?

To allow for efficient memory management and separation of processes. Signup and view all the answers

What can lead to thrashing in a system?

Running low on physical memory and constant paging. Signup and view all the answers

Why must other pages be stored on disk before loading new memory pages?

To make space in physical memory for new pages. Signup and view all the answers

What happens to the stack each time a function is called?

Grows Signup and view all the answers

Which memory area in C++ grows when memory is allocated with 'new'?

Heap Signup and view all the answers

What is the consequence of a program exceeding its maximum stack size?

Crash (stack overflow) Signup and view all the answers

In which direction does the heap generally grow in memory?

Upward Signup and view all the answers

Which memory area is shared among all threads in a running process?

Heap Signup and view all the answers

What condition is very unlikely to occur when allocating memory from the stack?

(Almost) always results in page faults Signup and view all the answers

What happens when a process accesses memory at a virtual address that is not backed by physical memory?

A page fault occurs and the memory page is loaded from disk into memory Signup and view all the answers

What is the purpose of dividing the address space into fixed-size blocks called memory pages?

To make virtual address space larger than physical address space Signup and view all the answers

What happens if a memory page needs to be evicted from main memory but has not been modified?

The page is evicted without any additional operations Signup and view all the answers

What is the consequence of having no more available page frames in main memory?

A hardware exception called a page fault takes place Signup and view all the answers

Which hardware exception occurs when a memory page is not mapped in the main memory?

Page fault Signup and view all the answers

What distinguishes iOS's handling of virtual memory from systems that support paging?

iOS does not store dirty pages on disk, only clean pages can be evicted from memory Signup and view all the answers

What is the main purpose of the custom allocator discussed in the text?

To handle all allocations using the stack instead of dynamic memory allocations Signup and view all the answers

What is the primary role of the functions allocate() and deallocate() in the custom allocator?

Forward requests to the arena for memory allocation and deallocation Signup and view all the answers

What does the rebind struct within the custom allocator template aim to do?

Change the type of elements stored in the allocator Signup and view all the answers

How are instances of ShortAlloc compared to ensure they are using the same arena?

By checking if they are pointing to the same arena Signup and view all the answers

Why is it beneficial to use an allocator and arena with a standard container?

To avoid unnecessary copies and move operations Signup and view all the answers

What is the primary state that the custom allocator holds?

Reference to the arena Signup and view all the answers

What is the main characteristic of the Mallocator struct described in the text?

Stateless allocator Signup and view all the answers

Which global functions are primarily used by the Mallocator struct for allocation and deallocation?

malloc() and free() Signup and view all the answers

What should be done when deallocating memory allocated with Mallocator?

Always deallocate with Mallocator instance Signup and view all the answers

Why is a stateless allocator considered the least complicated allocator to write?

It relies on external global state for allocation Signup and view all the answers

What makes a stateful allocator more preferable than a stateless allocator in certain scenarios?

Ability to reference specific instances Signup and view all the answers

How does the implementation of the arena class relate to the concept of stateful allocators?

Arenas benefit from stateful allocators to reference the arena instance Signup and view all the answers