Recent questions tagged tlb - GATE Overflow

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 55 (Page No. 261 - 262)
Write a program that can be used to compare the effectiveness of adding a tag field to $TLB$ entries when control is toggled between two programs. The tag field is used to effectively label each entry with the ... for a simple (but nontrivial) input example. Plot the number of $TLB$ updates per $1000$ references.

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.8k points) | 12 views

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 53 (Page No. 261)
Write a program that demonstrates the effect of $TLB$ misses on the effective memory access time by measuring the per-access time it takes to stride through a large array. Explain the main concepts behind the ... but for an older computer with a different architecture and explain any major differences in the output.

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.8k points) | 4 views

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 23 (Page No. 256)
How can the associative memory device needed for a $TLB$ be implemented in hardware, and what are the implications of such a design for expandability?

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.8k points) | 4 views

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 22 (Page No. 256)
A computer whose processes have $1024$ pages in their address spaces keeps its page tables in memory. The overhead required for reading a word from the page table is $5\: nsec.$ To reduce this overhead, the computer has a $TLB,$ ... a lookup in $1\: nsec.$ What hit rate is needed to reduce the mean overhead to $2\: nsec?$

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.8k points) | 11 views

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 16 (Page No. 255)
You are given the following data about a virtual memory system: The $TLB$ can hold $1024$ entries and can be accessed in $1$ clock cycle $(1\: nsec).$ A page table entry can be found in $100$ ... $0.01\%$ lead to a page fault, what is the effective address-translation time?

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.8k points) | 5 views

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 11 (Page No. 255)
Consider the following C program: int X[N]; int step = M; /* M is some predefined constant */ for (int i = 0; i < N; i += step) X[i] = X[i] + 1; If this program is run on a machine with ... for every execution of the inner loop? Would your answer in part $(a)$ be different if the loop were repeated many times? Explain.

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.8k points) | 2 views

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Self Doubt : Regarding TLB entry for a page not present in memory
If a page is not present in the memory, then its corresponding entry in the page table would have the ‘Present’ bit set as 0 to indicate , the page is not present. Will this entry be considered for caching in TLB? As I understand from above line in Tanenbaum, The entry should not be present in TLB. Is my understanding right?

asked May 9 in Operating System by Mayank0343 (357 points) | 42 views

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ISI2017-PCB-CS-5(b)
Consider a paging system with the page table stored in memory. If a memory reference takes $200$ nanoseconds, how long does a paged memory reference take? If we add a Translation Lookaside Buffer (TLB) and $75$ percent of all page-table references are ... memory reference time? Assume that finding a page-table entry in the TLB takes $20$ nanoseconds, if the entry is present.

asked Apr 8 in Operating System by akash.dinkar12 Boss (41.9k points) | 58 views

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Galvin Edition 9 Exercise 9 Question 15 (Page No. 452)
A simplified view of thread states is $Ready$, $Running$, and $Blocked$,where a thread is either ready and waiting to be scheduled, is running on the processor, or is blocked (for example, waiting for I/O). This is illustrated ... the thread change state if an address reference is resolved in the page table? If so, to what state will it change?

asked Mar 21 in Operating System by akash.dinkar12 Boss (41.9k points) | 28 views

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Galvin Edition 9 Exercise 9 Question 14 (Page No. 452)
Assume that a program has just referenced an address in virtual memory. Describe a scenario in which each of the following can occur. (If no such scenario can occur, explain why.) • $TLB$ miss with no page fault • $TLB$ miss and page fault • $TLB$ hit and no page fault • $TLB$ hit and page fault

asked Mar 21 in Operating System by akash.dinkar12 Boss (41.9k points) | 22 views

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Caching
Given the following information: TLB hit rate 95%, TLB access time is 1 cycle. cache hit rate 90 %, cache access time is 1 cycle. When TLB and cache both get miss; page fault rate is 1% The TLB access and acache access are ... cycles Access to hard drive requires 50,000 cycles. Compute the average memory access latencies when the cache is physically addresses (in cycles).

asked Mar 10 in CO and Architecture by s_dr_13 (179 points) | 120 views

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12

effective memory access time
A demand paging uses a TLB and a single level page table stored in main memory. The memory access time is 5s. The page fault service time is 25s. If 70% of access is in TLB and of the remaining, 20% is not present in the main memory. The effective memory access time is? Thanks!

asked Jan 27 in Operating System by Abhipsa Mishra (97 points) | 244 views

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TLB hit ration and memory lookup time
Consider a system where TLB lookup time is $25$ ns and memory access time is $200$ ns, respectively. Assuming a virtual address space of $2$ KB, page size of $32$ bytes, and a PTE size of $2$ bytes, what is the minimum TLB hit ratio that results in an average v2p (virtual to physical) translation latency of $185$ ns?

asked Jan 13 in Operating System by dd Veteran (57k points) | 79 views

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me test series
A computer system implements a 38 bit virtual address, page size of 16 KB, and 256 entries translation look aside buffer (TLB) organized into 32 sets each having 8 ways. If TLB tag does not store any process id. The minimum length of TLB tag in bits is____

asked Jan 11 in Operating System by newdreamz a1-z0 Active (1.6k points) | 41 views

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Os TLB question
How they calculated time for number of levels?

asked Dec 16, 2018 in Operating System by muthu kumar Active (1.7k points) | 150 views

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MadeEasy Subject Test 2019: Operating System - Translation Lookaside Buffer
A TLB is a hardware device used for speeding up the conversation from virtual address to physical address. Consider a memory management unit where a memory reference takes 500 nanoseconds; TLB (Translation Look aside Buffer) reference ... EMAT using TLB ==> 640ns EMAT wthout TLB ==> 1000ns how to calculate speed Up.?

asked Dec 13, 2018 in Operating System by jatin khachane 1 Loyal (7.3k points) | 78 views

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TLB OS
Why the formula used here is not P(10) + (1-P)(50) = 20 ?; A computer keeps its page tables in memory. The time required to read a word from the page table is 50ns. To reduce this overhead, the computer has a TLB, which holds 32 (virtual page, physical page frame) pairs and can ... : 10ns + (1 - p) 50ns = 20ns p =4/5 = .80 The TLB hit rate has to be 80% for a mean access time of 20ns.

asked Dec 3, 2018 in Operating System by rahuljai Junior (551 points) | 220 views

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ace test series
A computer whose processes have 1024 pages in their address spaces keeps its page tables in memory. The overhead required for reading a word from the page table is 500 nsec. To reduce this overhead, the computer has tlb which holds 32 entries and can do look up in 100 nsec. What hit rate is needed to reduce the mean overhead to 200 nsec? can anyone solve this

asked Nov 28, 2018 in Operating System by vijju532 Active (1k points) | 100 views

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19

TLB Effective Access Time

asked Nov 28, 2018 in CO and Architecture by Balaji Jegan Active (4.9k points) | 325 views

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20

SudoGate Test Series - Virtual Memory
A computer system has TLB access time = 30 ns and the main memory access time is 150 ns and if the miss rate is 20 % the calculate the effective memory access time if 3 level of paging is applied. i am getting 270 ns

asked Nov 5, 2018 in Operating System by Gurdeep Saini Boss (10.3k points) | 124 views

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21

Virtual Memory
Which of the following is true? A. If the page size increases page fault rate may also increase. B. Multi-level paging optimizes program execution time. C. Dynamic linking increases program execution time.Correct Option D. TLB is a software data structure.

asked Jul 18, 2018 in Operating System by Na462 Loyal (6.9k points) | 155 views

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caching and virtual memory
I am having troble with these following questions. Please I need help

asked Apr 19, 2018 in Operating System by Samson Bankole (5 points) | 82 views

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23

Does every process have its own TLB?
I know that every process has its own page table and but is it the same with TLB? Does every process have its own TLB or there is a master TLB which is used by all the processes?

asked Apr 6, 2018 in Operating System by punkprincess (35 points) | 523 views

+3 votes

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My doubt on TLB and page fault
First read this whole thing what I am writing below: Case 1: If we have to access unit address in memory using TLB and we assume that no page fault occurs then, EMAT=p( T+M )+( 1-p ) (T+M+M) T=TLB access time, M= ... if there page fault occurs then how does the last calculated EMAT here affects the first Estimated memory access time which we have calculated using TLB?

asked Apr 5, 2018 in Operating System by Akash Kumar Roy Junior (559 points) | 393 views

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25

TLB JUST FOR KNOWLEDGE
TLB IS EITHER HARDWARE OR SOFTWARE PLZ EXPLAIN BRIEFLY?????

asked Dec 16, 2017 in CO and Architecture by Sunidhi chauhan Junior (581 points) | 46 views

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26

OS TLB
compute system implement a 36-bit virtual address page size of 16KB and a 256-entry translation look aside buffer organized into 64 sets each having four ways.assume that the TLB tag does not store any process id. the minium length of the TLB tag in bits is?

asked Dec 12, 2017 in Operating System by Akshay Koli 4 Active (1.3k points) | 181 views

+3 votes

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TLB buffer
My doubt is Sorry if its silly. 1. TLB Maps from VA --> PA, so when its accessed ? is it when cpu generates logical address and by hardware it get convert into virtual address and then tlb is looked to convert into physical address. 2. When a ... Virtual address space to physical address space i.e. TLB Stores frequent mapping of pages. So where is actually TLB Stored is it in cache?

asked Nov 26, 2017 in CO and Architecture by Na462 Loyal (6.9k points) | 185 views

+2 votes

2 answers

28

Memory overhead in Multilevel paging with TLB
Consider a computer system using 2-level paging with TLB.The logical address supported is 32 bits.The page table is divided into 512 pages each of size 1K.The memory access time is 100ns and the TLB access time 15ns .Page table entry size at 1st ... page table along with the page of the second level page table for a process? A)6KB B)4KB C)5KB D)12KB

asked Nov 23, 2017 in Operating System by raks8877 (27 points) | 1.1k views

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29

Effective memory access time
please explain how to understand this problem

asked Nov 20, 2017 in CO and Architecture by Parshu gate Active (3.1k points) | 961 views

+2 votes

2 answers

30

TLB HITS
What is the average memory access time (correct to two decimal places) when you have the following memory hierarchy? Assume that (i) the cache uses physical addresses, (ii) the CPU stalls until the data is delivered, (iii) everything fits into the memory, and (iv) the hardware does the page table walk and updates TLB.

asked Nov 12, 2017 in Databases by Parshu gate Active (3.1k points) | 214 views

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