In a Virtual Address translation to Physical Address, the one main reason we use the Write Back scheme instead of Write Through in our caches is because: O Disk memory access time takes millions of cycles compared to a few cycles at cache level O The Write Through strategy needs buffers for speedup which makes it incompatible with a Virtual Memory Address translation O Write Through is very costly to implement compared to write back O The replacement of a translation in the TLB (in the event of a Page Fault) is incompatible with the Write Through strategy,

In a Virtual Address translation to Physical Address, the one main reason we use the Write Back scheme instead of Write Through in our caches is because: O Disk memory access time takes millions of cycles compared to a few cycles at cache level O The Write Through strategy needs buffers for speedup which makes it incompatible with a Virtual Memory Address translation O Write Through is very costly to implement compared to write back O The replacement of a translation in the TLB (in the event of a Page Fault) is incompatible with the Write Through strategy,

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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You have a virtual memory system with a two-entry TLB, a 2-way set associative cache and a page table for a process P. Assume cache blocks of 8 bytes and page size of 16 bytes. In the system below, main memory is divided up into blocks, where each block is represented by a letter. Two blocks equals one frame. A) Virtual address page 3, offset 7 results in a TLB hit or miss? If TLB hit, what’s the main memory frame? If TLB miss, would it result in a page fault? If not a page fault, what’s the main memory frame and what the physical address in binary? Explain your answers. B) Virtual address page 0, offset 1310 results in a TLB hit or miss? If TLB hit, what’s the main memory frame? If TLB miss, would it result in a page fault? If not a page fault, what’s the main memory frame? Explain your answers. C) Virtual address page 2, offset 3 results in a TLB hit or miss? If TLB hit, what’s the main memory frame? If TLB miss, would it result in a page fault? If not a page fault, what’s…
Assume a direct-mapped cache that holds 4096 bytes, in which each block is 16 bytes. Assuming that an address is 32 bits and that cache is initially empty, complete the table that follows.(You should use hexadecimal numbers for all answers.) Which, if any, of the addresses will cause a collision (forcing the block that was just brought in to be overwritten) if they are accessed one right after the other?
Here is the question: A direct-mapped cache consists of 8 blocks. A byte-addressable main memory contains 4K blocks of eight bytes each. Access time for the cache is 20 ns and the time required to fill a cache slot from main memory is 300 ns. Assume a request is always started in sequential to cache and then to main memory. If a block is missing from cache, the entire block is brought into the cache and the access is restarted. Initially, the cache is empty. b) Compute the hit ratio for a program that loops 3 times from address 0 to 75 (base 10) in memory. For b, another example has been provided in regards to a previous problem: A direct-mapped cache consists of eight blocks. Main memory contains 4K blocks of eight words each. Access time for the cache is 22 ns and the time required to fill a cache slot from main memory is 300ns (this time will allow us to determine the block is missing and bring it into cache). Assume a request is always started in parallel to both cache and to…
What are some of the reasons why it is difficult to create a cache replacement policy that is optimal for all address sequences?
In this exercise, we will examine space/time optimizations for page tables. The following list provides parameters of a virtual memory system. Virtual Address (bits) Physical DRAMInstalled Page Size PTE Size (byte) 43 16 GiB 4 KiB 4 For a single-level page table, how many page table entries (PTEs) are needed? How much physical memory is needed for storing the page table? Using a multilevel page table can reduce the physical memory consumption of page tables, by only keeping active PTEs in physical memory. How many levels of page tables will be needed in this case? And how many memory references are needed for address translation if missing in TLB? An inverted page table can be used to further optimize space and time. How many PTEs are needed to store the page table? Assuming a hash table implementation, what are the common case and worst case numbers of memory references needed for servicing a TLB miss?
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Draw a line between a cache that is fully associative and one that is directly mapped out.
Let's pretend a block is being returned from the write buffer to main memory when the processor makes a partially-completed request to the cache. It is expected that this timeline of events will play out.
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