Help with computer engineering problem

Click For Summary

Discussion Overview

The discussion revolves around a computer engineering problem related to cache memory, specifically focusing on the definitions and implications of 2-way and 4-way caches. Participants explore the effects of these cache types on the problem at hand, as well as the calculations for tag lengths.

Discussion Character

  • Homework-related, Technical explanation

Main Points Raised

  • One participant expresses difficulty in approaching the problem and seeks guidance.
  • Another participant emphasizes the need for the original poster to demonstrate effort by defining 2-way and 4-way caches and discussing their effects.
  • A participant claims to have calculated tag lengths, stating 15 bits for part a and 14 bits for part b, but does not provide the methodology behind these calculations.
  • A follow-up request is made for the participant to show their working process for the calculations provided.

Areas of Agreement / Disagreement

There is no clear consensus on the solutions to the problem, as participants are still discussing definitions and calculations. Multiple viewpoints and requests for clarification remain present.

Contextual Notes

The discussion lacks detailed definitions of 2-way and 4-way caches, as well as the specific assumptions or parameters used in the calculations for tag lengths.

imixerik
Messages
2
Reaction score
0
Homework Statement
Consider a system that can host 64 GB of memory and has 8MB of L3 cache. Suppose that each cache line contains 4 chunks, each of size 16B.

a) Assuming 4-way associative cache, what are the lengths (in bits) of the following: tag, cache index, and block offset?

b) How does this change for a 2-way cache?

c) Suppose that if L3 is organized as 2-way, the access time is 20 cycles, but increases to 22 cycles if organized as 4-way, but the miss probability from L3 decrease from 12% to 10%. Suppose that the misses from L3 go to memory, and the average memory latency is 64 cycles. State which option is better and why.

d) Now suppose that the L2 cache can be organized as direct map or 4-way. In the first case, the L2 limited CPI (i.e., CPI if there is no miss out of L2) is 3.5 and MPI out of L2 is 0.08. In the second case, the CPI increases to 3.8 but the MPI is 0.06. Determine the best configuration for this system by considering all four possibilities: (i) DM L2, 2-way L3, (ii) DM L2, 4-way L3, (iii) 4-way L2, 2-way L3, and (iv) 4-way L2, 4-way L3.
Relevant Equations
Not sure what equations to use
Have been trying to figure out this problem for quite some time but don't know how to approach it.
 
Physics news on Phys.org
You need to show some effort on your schoolwork questions before we can offer tutorial help.

Start by defining 2-way and 4-way caches for us please. What effects will the differences have on this problem?
 
berkeman said:
You need to show some effort on your schoolwork questions before we can offer tutorial help.

Start by defining 2-way and 4-way caches for us please. What effects will the differences have on this problem?
Hey,

I worked through the problem and would like to believe I reached the correct solution for a and b. For a, i got 15 bits for the tag length and for b, i got 14 bits for the tag length.
 
imixerik said:
Hey,

I worked through the problem and would like to believe I reached the correct solution for a and b. For a, i got 15 bits for the tag length and for b, i got 14 bits for the tag length.
Great! Can you show us how you worked the numbers to get those answers? :smile:
 

Similar threads

Comp Sci Why is distributed computing/system important/necessary for big data?
  • · Replies 1 ·
Replies
1
Views
2K
What is computational physics and what is the best way or method to learn computational physics?
  • · Replies 7 ·
Replies
7
Views
3K
Engineering I need guidance to choose my electives as computer engineering student
  • · Replies 2 ·
Replies
2
Views
2K
Engineering Systems Engineering QFD on an Aerial Fire Fighting Aircraft
  • · Replies 5 ·
Replies
5
Views
2K
Final project ideas using Noether's theorem in simulation class
  • · Replies 4 ·
Replies
4
Views
2K
Programs Looking for Computer Engineering advice (going into 8th grade next year)
  • · Replies 18 ·
Replies
18
Views
2K
Learning Assembly and computer architecture for x86
  • · Replies 102 ·
4
Replies
102
Views
4K
Considering Switching from Physics to Computer Engineering
  • · Replies 7 ·
Replies
7
Views
3K
Engineering Reviewing Efficiency of Otto & Diesel Cycle Heat Engines
  • · Replies 8 ·
Replies
8
Views
4K
Engineering Active and reactive effect in AC circuit
  • · Replies 2 ·
Replies
2
Views
1K