In the context of memory management, what are placement and replacement algorithms?

Correct Answer: We encounter cycle stealing in the context of Direct Memory Access (DMA) Either the DMA controller can use the data bus when the CPU does not need it, or it may force the CPU to temporarily suspend operation The latter technique is called cycle stealing Note that cycle stealing can be done only at specific break points in an instruction cycle

Correct Answer: Resident set is that portion of the process image that is actually in real-memory at a particular instant Working set is that subset of resident set that is actually needed for execution (Relate this to the variable-window size method for swapping techniques)

Correct Answer: In a cached system, the base addresses of the last few referenced pages is maintained in registers called the TLB that aids in faster lookup TLB contains those page-table entries that have been most recently used Normally, each virtual memory reference causes 2 physical memory accesses- one to fetch appropriate page-table entry, and one to fetch the desired data Using TLB in-between, this is reduced to just one physical memory access in cases of TLB-hit

Correct Answer: Long term scheduler determines which programs are admitted to the system for processing It controls the degree of multiprogramming Once admitted, a job becomes a process Medium term scheduling is part of the swapping function This relates to processes that are in a blocked or suspended state They are swapped out of real-memory until they are ready to execute The swapping-in decision is based on memory-management criteria Short term scheduler, also know as a dispatcher executes most frequently, and makes the finest-grained decision of which process should execute next This scheduler is invoked whenever an event occurs It may lead to interruption of one process by preemption

Correct Answer: It is a phenomenon in virtual memory schemes when the processor spends most of its time swapping pages, rather than executing instructions This is due to an inordinate number of page faults

Correct Answer: For load-time dynamic linking: Load module to be loaded is read into memory Any reference to a target external module causes that module to be loaded and the references are updated to a relative address from the start base address of the application module With run-time dynamic loading: Some of the linking is postponed until actual reference during execution Then the correct module is loaded and linked

Correct Answer: It does not have the features like ability to support multiple processors virtual storage source level debugging

Correct Answer: When the OS at the explicit request of another process creates a process, this action is called process spawning

Correct Answer: Windows NT uses protection mechanism called rings provides by the process to implement separation between the user mode and kernel mode

Correct Answer: It is the transfer of sufficient amount of the state of process from one machine to the target machine