Virtual Memory and Memory Management

Virtual memory is a facility that allows programs to address memory from a logical point of view, without regard to the amount of main memory physically available. It allows the address fields of machine instructions to contain virtual addresses.

The MMU translates each virtual address into a physical address in main memory for reads to and writes from main memory.

A logical cache, or virtual cache, stores data using virtual addresses and allows the processor to access the cache directly. A physical cache stores data using main memory physical addresses.

<p>The disadvantage of logical cache is that each application sees the same virtual memory address space, so the same virtual address in two different applications refers to two different physical addresses, requiring the cache to be flushed with each application context switch or extra bits to be added to each line of the cache.</p> Signup and view all the answers

<p>The cache can be placed between the processor and the MMU, or between the MMU and main memory.</p> Signup and view all the answers

<p>Cache memory is intended to give memory speed approaching that of the fastest memories available, and at the same time provide a large memory size.</p> Signup and view all the answers

<p>When the processor attempts to read a word of memory, a check is made to determine if the word is in the cache. If so, the word is delivered to the processor. If not, a block of main memory is read into the cache and then the word is delivered to the processor.</p> Signup and view all the answers

<p>Because of the phenomenon of locality of reference, when a block of data is fetched into the cache to satisfy a single memory reference, it is likely that there will be future references to that same memory location or to other words in the block.</p> Signup and view all the answers

<p>The L2 cache is slower and typically larger than the L1 cache, and the L3 cache is slower and typically larger than the L2 cache.</p> Signup and view all the answers

<p>Multiple levels of cache are used to provide varying speeds and memory sizes, with each level serving as a buffer between the processor and the main memory.</p> Signup and view all the answers