Recent questions tagged tlb

+1 vote

1 answer

1

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 Debashish Deka Veteran (57.8k points) | 34 views

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1 answer

2

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 (1.2k points) | 27 views

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1 answer

3

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

asked Dec 16, 2018 in Operating System by muthu kumar Active (1.1k points) | 66 views

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1 answer

4

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 (437 points) | 106 views

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0 answers

5

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 (1.1k points) | 65 views

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0 answers

6

TLB Effective Access Time

asked Nov 28, 2018 in CO & Architecture by Balaji Jegan Active (4.6k points) | 95 views

0 votes

1 answer

7

sudo gate test series
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 Loyal (7.7k points) | 95 views

0 votes

1 answer

8

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 (8.1k points) | 102 views

0 votes

0 answers

9

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 (7 points) | 69 views

+2 votes

0 answers

10

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 (47 points) | 271 views

+2 votes

1 answer

11

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 (527 points) | 244 views

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12

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

asked Dec 16, 2017 in CO & Architecture by Sunidhi chauhan Junior (543 points) | 40 views

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0 answers

13

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) | 125 views

+3 votes

1 answer

14

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 & Architecture by Na462 Loyal (8.1k points) | 151 views

+1 vote

2 answers

15

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 (29 points) | 773 views

0 votes

0 answers

16

Effective memory access time
please explain how to understand this problem

asked Nov 20, 2017 in CO & Architecture by Parshu gate Active (5.1k points) | 790 views

+2 votes

2 answers

17

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 (5.1k points) | 155 views

+4 votes

1 answer

18

Virtual Memory

asked Oct 25, 2017 in Operating System by Shivam Chauhan Loyal (9.1k points) | 195 views

+3 votes

0 answers

19

Effective memory access time
What has to be the general and final formula for calculating the effective memory access time, taking in consideration the $\alpha$-level page table, TLB hit ratio as $h$, miss ratio as $m$, memory access time as $M$ ... for page fault servicing as $x$? There seems to be so many formulae, each different from each other depending on the question.

asked Aug 18, 2017 in CO & Architecture by habedo007 Active (2.3k points) | 357 views

+1 vote

1 answer

20

Multilevel TLB performance
A computer has a 128-entry $L_1$ TLB, 1024-entry $L_2$ TLB, and uses page size of 4KB. A program reads a 1MB array, one byte at a time from start to end, 10 times. Assuming the TLBs are directly mapped and initially empty, and no other memory is accessed, find TLB hits and misses of both $L_1$ and $L_2$ TLB (array is page aligned).

asked Aug 8, 2017 in Operating System by habedo007 Active (2.3k points) | 239 views

+3 votes

1 answer

21

Self-doubt
Can there ever be a TLB hit and a page fault?

asked Jul 23, 2017 in Operating System by just_bhavana Boss (12.3k points) | 288 views

+1 vote

0 answers

22

tlb segmentation paging
Consider a memory system consists of a single external cache with an access time of 30ns and a hit rate of 0.85, and a main memory with an access time of 80ns. Now we add virtual memory to the system. The TLB is implemented internal to the processor chip and takes ... memory access time of the system with virtual memory?( Marks: 0.00 ) 8ns 30ns 40ns 51ns

asked Jan 17, 2017 in Operating System by Neal Caffery Active (1.2k points) | 304 views

0 votes

2 answers

23

TLB paging
Consider a system with 2-levels of paging and a TLB with hit rate of 95% and TLB access time of 1ns. Find the effective memory access time if there’s a data cache whose hit rate is 85% and cache access time is 1ns, and main memory access time is 100ns. 100ns. 27ns 25ns 30ns 20ns

asked Jan 17, 2017 in Operating System by Neal Caffery Active (1.2k points) | 852 views

+4 votes

0 answers

24

TLB and paging
Consider the following piece of code which multiplies two matrices: int a[1024][1024], b[1024][1024], c[1024][1024]; multiply() { unsigned i, j, k; for(i = 0; i < 1024; i++) for(j = 0; j < 1024; j++) for(k = 0; k < ... requires 4 bytes for storage. Compute the number of TLB misses if the page size is 4096 and the TLB has 8 entries with a replacement policy consisting of LRU.

asked Jan 5, 2017 in Operating System by sushmita Boss (16.6k points) | 231 views

+5 votes

3 answers

25

Operating System: Cache
A processor uses 2 level paging for virtual address to physical address translation. page tables for both levels are stored in physical memory. there is physically addressed cache. TLB hit ratio = 96% TLB Access Time=1ns Cache hit ratio=90% Cache Access Time= 1ns Physical M/M Access Time: 10 ns What is effective memory access time?

asked Jan 5, 2017 in Operating System by Vijay Thakur Boss (17.2k points) | 717 views

+1 vote

1 answer

26

Computing Effective Memory access time - Cache organization
Consider the following information about a hypothetical processor. Assume the cache is physically addressed TLBHit Rate: 95% access time 1 cycle Cache Hit Rate: 90% access time 1 cycle when tlb and cache both get miss, page fault rate 1% TLB access and ... 1 + .1(5+ .01(100) ) = 2.675 Could someone pls point out the flaw in the logic?

asked Dec 26, 2016 in CO & Architecture by yg92 Active (3.4k points) | 430 views

0 votes

0 answers

27

TLB concept
As cache is divided into no of blocks same as physical address space... Does the TLB is also divided..??

asked Dec 21, 2016 in Operating System by vaishali jhalani Loyal (6k points) | 281 views

+9 votes

1 answer

28

virtually/physically tagged caches
can some one please clearly explain ,what is 1. virtually indexed virtually tagged cache 2. physically indexed physically tagged cache 3. virtually indexed physicaly tagged cache it is very confusing ,these concepts are used in finding effective memory access in questions of gate.

asked Nov 9, 2016 in CO & Architecture by Akriti sood Boss (13.8k points) | 840 views

+2 votes

3 answers

29

TLB hit ratio
Consider a paging system uses, TLB’s access time is 30 ns and memory access time is 200ns. If the effective memory access time is 150ns, what will be the hit ratio of TLB?

asked Nov 8, 2016 in Operating System by Veerendra V (445 points) | 2.5k views

+1 vote

2 answers

30

Virtually indexed caches
What is virtual indexed cache? How is it different from physical indexed cache? What is virtually indexed physical tagged cache? If possible point me to proper resources.

asked Nov 6, 2016 in Operating System by Veerendra V (445 points) | 577 views

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