OS day 3

Which of the following page replacement algorithms suffers from Belady’s Anomaly?

• Optimal replacement

• LRU

• FIFO

• Both optimal replacement and FIFO

When a page is selected for replacement, and its modify bit is set ____________

• the page is clean

• the page has been modified since it was read in from the disk

• the page is dirty

• the page has been modified since it was read in from the disk & page is dirty

LRU page – replacement algorithm associates with each page the ______

• time it was brought into memory

• the time of that page’s last use

• page after and before it

• all of the mentioned

A process is thrashing if ____________

• it spends a lot of time executing, rather than paging

• It spends a lot of time paging than executing

• it has no memory allocated to it

• none of the mentioned

Thrashing _______ the CPU utilization.

• increases

• keeps constant

• decreases

• none of the mentioned

The DMA transfers are performed by a control circuit called as __________

• Device interface

• DMA controller

• Data controller

• Overlooker

After the completion of the DMA transfer, the processor is notified by __________

• Acknowledge signal

• Interrupt signal

• WMFC signal

• None of the mentioned

The DMA transfer is initiated by _____

• Processor

• The process being executed

• I/O devices

• OS

Can a single DMA controller perform operations on two different disks simultaneously?

• True

• False