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Paged memory is used to extend the real physical memory of the machine by copying blocks of data from the memory to a drive. That way you can run many programs simultaneously even if they consume more memory than you physically have in your computer. When a program requires to access the data that is "paged to disk" the operating system will read this data into memory.
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What is paged pool memory?
Paged pool memory is a region in virtual memory which can be paged in and paged out of the system. Device driver which do not need to access the memory from DPC/Dispatch level or above can use paged pool. it is accessible from any process context.
What is non paged pool memory?
resident memory pool: cannot be swapped out
In paged system Can the logical address space b larger than physical address space?
Yes. This is the fundamental premise of paged or virtual memory - that you can have more logical memory than physical memory.
If a memory reference takes 200 nanoseconds how long does a paged memory reference take?
twice
Does a paged memory management system have the fragmentation problem at process image level?
No, not at all
What is the difference between swap and real memory?
Data that has been paged or swapped out exist on swap/page files on disks. The data can be paged or swapped back into real memory when it is required. Data in real memory (typically RAM) can be accessed directly by the CPU. Accessing data in real memory is hundreds or thousands times quicker than accessing it via disk.
What is passed as an argument to device driver when page is swapped out to write that page in swap area?
Memory paging has nothing to do with device drivers. When memory needs to be written to but that memory is currently paged out (to disk), a page fault occurs. To resolve the fault, the system memory manager must make physical memory available to load the required page, which means the current content of that memory needs to be paged out. In other words, the memory manager swaps the pages.
Why are page files used?
On a 32-bit system it is only possible to address a maximum of 2^32 bytes of memory (4,294,967,296 bytes which is 4 gigabytes). Memory is allocated in contiguous blocks such that if your program requires x bytes of memory, a block of x contiguous bytes must be available to meet the allocation request. If there is no single block large enough to meet the required allocation, you will get an out of memory error, even if there's more than x bytes of physical memory available in total. To avoid these problems, we use virtual memory. If there is no single block available to meet an allocation, existing allocations can be temporarily moved to a page file, thus freeing up the physical memory. When memory that has been paged out is required, other allocations can be paged out to allow the required memory to be paged in. Given that the contents of memory are swapped to and from the page file, the page file is often called a swap file. Data that was paged out of one physical address may be paged in to a completely different physical address. However, the virtual address does not change; the memory manager performs the translation between the physical and virtual addresses. This makes it possible for a 32-bit system to operate with a full complement of 4 gigabytes of memory even when the system has less than 4 gigabytes of physical memory installed. 64-bit systems allow us to address 18,446,744,073,709,551,616 bytes of memory which is far more memory than physically exists on the planet! For practical reasons, we can only use a small fraction of the full address space, however page files and virtual memory make it possible to use far more addresses than might be physically available.
What is defined as the condition that occurs when your system is running out of virtual memory?
When a PC runs low on virtual memory, system activity causes what is called "thrashing", when memory is repeatedly paged out to, and read back from, the hard drive.
What rhymes with Enraged?
paged
What are the recent memory management schemes?
Single-user contiguous Fixed Partitions Dynamic Partitions Relocatable Dynamic Partitions Paged Memory Allocation Demand Paging Working Set Segmented Memory Allocation Segmented/Demand Page Memory Allocation -------Taken from "Understanding Operating Systems. 6th edition pg 99
What are Outings?
A page out is when a page from memory is written to disk. If you have a program/application that needs alot of computer memory, the CPU can break up the program and run in memory the only part it currently needs. Once that part is finished it can be paged out and the next part paged in. Using the disk drive allows the computer to run larger jobs than those that would only fit into memory. Using the disk drive to swap out pages will cause the program to run slower. It's a trade off. Today's computer has much more memory that what was available in the past and the need for paging and swaping isn't as important as it once was. It is still used today.
