Recent questions tagged tlb

Recent questions tagged tlb

3 votes

2 answers

1

GATE CSE 2022 | Question: 28
Which one of the following statements is $\text{FALSE}?$ The $\text{TLB}$ performs an associative search in parallel on all its valid entries using page number of incoming virtual address. If the virtual address of a word given by $\text{CPU}$ has a ... $\text{V2}$ map to the same value while hashing, then the memory access time of these addresses will not be the same.

Arjun asked in Operating System Feb 15

by Arjun

998 views

0 votes

3 answers

2

Applied Test Series
A computer system has a page size of 1024 bytes and maintains the page table for each process in main memory. The overhead required for doing a lookup in the page table is 500 ns. To reduce this overhead, the computer has a TLB that ... frame mappings. A TLB lookup requires 100ns. Which TLB hit-rate will ensure an average virtual address translation time of exactly 200ns?

LRU asked in Operating System Jan 11

by LRU

215 views

1 vote

1 answer

3

Applied Practice test
Suppose: TLB lookup time = 20 ns TLB hit ratio = 80% Memory access time = 75 ns PFST = 500,000 ns 50% of the pages are dirty OS uses a single level page table What is the approximated effective access time (EAT) if we assume the page fault rate is 10%? Assume the cost to update the TLB, the page table, and the frame table (if needed) is negligible.

darshak_devani asked in Operating System Oct 18, 2021

by darshak_devani

321 views

2 votes

2 answers

4

UGC NET CSE | October 2020 | Part 2 | Question: 18
Consider a single-level page table system, with the page table stored in the memory. If the hit rate to TLB is $80\%$, and it takes $15$ nanoseconds to search the $TLB$, and $150$ nanoseconds to access the main memory, then what is the effective memory access time, in nanoseconds? $185$ $195$ $205$ $175$

go_editor asked in Operating System Nov 20, 2020

1.2k views

2 votes

2 answers

5

NIELIT 2017 July Scientist B (CS) - Section B: 32
A CPU generates $32$-bit virtual addresses. The page size is $4$ KB. The processor has a Translation Look-aside Buffer (TLB) which can hold a total of $128$ page table entries and is $4$-way set associative. The minimum size of the TLB tag is $\text{11 bits}$ $\text{13 bits}$ $\text{15 bits}$ $\text{20 bits}$

Lakshman Patel RJIT asked in Operating System Mar 30, 2020

by Lakshman Patel RJIT

693 views

0 votes

0 answers

6

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.

Lakshman Patel RJIT asked in Operating System Oct 26, 2019

by Lakshman Patel RJIT

204 views

0 votes

0 answers

7

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.

Lakshman Patel RJIT asked in Operating System Oct 26, 2019

by Lakshman Patel RJIT

248 views

0 votes

0 answers

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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?

Lakshman Patel RJIT asked in Operating System Oct 26, 2019

by Lakshman Patel RJIT

173 views

1 vote

1 answer

9

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 $2\: nsec?$

Lakshman Patel RJIT asked in Operating System Oct 26, 2019

by Lakshman Patel RJIT

403 views

1 vote

1 answer

10

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?

Lakshman Patel RJIT asked in Operating System Oct 26, 2019

by Lakshman Patel RJIT

297 views

1 vote

1 answer

11

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.

Lakshman Patel RJIT asked in Operating System Oct 26, 2019

by Lakshman Patel RJIT

220 views

0 votes

1 answer

12

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?

Mayank0343 asked in Operating System May 9, 2019

297 views

1 vote

1 answer

13

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.

akash.dinkar12 asked in Operating System Apr 8, 2019

by akash.dinkar12

2.1k views

0 votes

1 answer

14

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?

akash.dinkar12 asked in Operating System Mar 21, 2019

by akash.dinkar12

270 views

0 votes

1 answer

15

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

akash.dinkar12 asked in Operating System Mar 21, 2019

by akash.dinkar12

765 views

1 vote

0 answers

16

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).

s_dr_13 asked in CO and Architecture Mar 10, 2019

785 views

0 votes

0 answers

17

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!

Abhipsa asked in Operating System Jan 27, 2019

718 views

2 votes

1 answer

18

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?

dd asked in Operating System Jan 13, 2019

by dd

440 views

0 votes

1 answer

19

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____

newdreamz a1-z0 asked in Operating System Jan 11, 2019

by newdreamz a1-z0

208 views

0 votes

0 answers

20

UPPCL AE 2018:57
Consider the following $\text{C}$ function executed in an $\text{OS}$ with paging where the page size is $4$ kilobytes. Further, assume that the system employs a $32-$ entry direct mapped $\text{TLB}$ int *alloc_and_init() { int counter, value = 0, size = 2048; int ... of the program, what is the number of $\text{TLB}$ misses during the execution of the for loop? $2048$ $2$ $0$ $1$

Lakshman Patel RJIT asked in Operating System Jan 5, 2019

by Lakshman Patel RJIT

102 views

1 vote

1 answer

21

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

muthu kumar asked in Operating System Dec 16, 2018

1.1k views

0 votes

1 answer

22

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.?

jatin khachane 1 asked in Operating System Dec 13, 2018

by jatin khachane 1

522 views

0 votes

1 answer

23

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.

rahuljai asked in Operating System Dec 3, 2018

877 views

0 votes

1 answer

24

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

vijju532 asked in Operating System Nov 28, 2018

411 views

0 votes

0 answers

25

TLB Effective Access Time

Balaji Jegan asked in CO and Architecture Nov 28, 2018

by Balaji Jegan

863 views

0 votes

0 answers

26

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

Gurdeep Saini asked in Operating System Nov 5, 2018

by Gurdeep Saini

375 views

1 vote

2 answers

27

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.

Na462 asked in Operating System Jul 18, 2018

by Na462

1.1k views

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