Question from OS
In a system that uses paging, a process cannot access memory that belongs to another process. Why? Why is it theoretically possible with segmentation but not paging?
An address on a paging system is a logical page number and an offset. The physical page is found by searching a table based on the logical page number to produce a physical page number. Because the operating system controls the contents of this table, it can limit a process to accessing only those physical pages allocated to the process. There is no way for a process to refer to a page it does not own because the page will not be in the page table. To allow such access, an operating system simply needs to allow entries for non-process memory to be added to the process page table. This is useful when two or more processes need to exchange data they just read and write to the same physical addresses (which may be at varying logical addresses). This makes for very efficient inter process communication. With segmentation, you only need a small amount of information - the segment descriptor - to share, instead of changing protection on a large number of pages. In addition, you don't have to worry about mapping the code to the same address - the addresses within the code are relative to the segment, so it can be relocated more easily.
Question from OS In a system that uses paging, a process cannot access memory that belongs...
Question 30 7 pts Consider a computer system that uses virtual memory with paging with a TUB. Suppose main memory access time is 10 ns and the time to look up the TLB 1 ns. Assume no page faults and the TLB has a hit of 95%. What is the effective memory access time (express in ns)
7 pts Question 30 Consider a computer system that uses virtual memory with paging with a TLB. Suppose main memory access time is 10 ns and the time to look up the TLB 1 ns. Assume no page faults and the TLB has a hit of 95%. What is the effective memory access time (express in ns) 11ns
Consider a demand-paging system with a paging disk that has an average access and transfer time of 20 milliseconds. Addresses are translated through a page table in main memory, with an access time of 1 microsecond per memory access. Thus, each memory reference through the page table takes two accesses. To improve this time, we have added an associative memory that reduces access time to one memory reference, if the page-table entry is in the associative memory. Assume that 80...
A computer uses virtual memory implemented by paging. The TLB lookup takes 100 ns and the update takes 200 ns. The PT lookup takes 1 µs and the update takes 2 µs. Loading a word from main memory onto the CPU takes 10 µs and loading a page from the disk into main memory takes 10 ms. The TLB hit ratio is 0.4 and the main memory hit ratio is 0.3. Compute the average access time for a referenced word:...
2. A computer uses virtual memory implemented by paging. The TLB lookup takes 150 ns and the update takes 300 ns. The PT lookup takes 2 us and the update takes 4 us. Loading a word from main memory onto the CPU takes 25 us and loading a page from the disk into main memory takes 20 ms. The TLB hit ratio is 0.3 and the main memory hit ratio is 0.4. Compute the average access time for a referenced...
Consider a computer system that uses a paging system. The memory contains 16 frames, each frame can accommodate 512 memory locations (size of frame = 512). The page table is as follows: Page Number 0 1 2 3 4 5 6 7 Frame Number 5 3 10 0 2 9 11 14 What are the physical addresses for the following logical addresses? Show your work Logical Address Physical Address 2345 1024 6780
Address Translation Question [8 points] Suppose a computing system uses paging with a logical address of 24 bits and a physical address of 32 bits. The page size is 4KB. Answer each of the following. If an answer is a power of 2, you can leave it in the form of a power of 2. ... 2. [20 points] Memory address translation and TLB performance [8 points] Suppose a computing system uses paging with a logical address of 24 bits...
Operating System! Please provides the answer for the following Question? How does the OS have direct privilege access to system software ? Why do we need only the OS to have direct privilege access to system software? How does the OS ensure the applications are isolated and protected from one and another? How does the OS have direct privilege access over computer hardware?
Q. 2. (a) Suppose the OS on your computer uses the buddy system for memory management. Initially the system has a 1 megabyte (1024K) block of memory available, which begins at address 0.Show the results of each request/release. (7.5) A: Request 400 K B: Request 15K C: Request 100K D: Request 80 K E: Request 25 K After memory is allocated to process E, how much internal fragmentation exists in the system. (b) Assume you have a computer system with...
Consider an OS that uses the buddy system for memory management. Initially it has one block of 256K at address 0. After successive requests for 6K, 19K, 53K, and 25K are processed, how many blocks are left and what are their sizes and addresses?