Major problems associated in writing with cache memories, Computer Engineering

Assignment Help:

Q. Major problems associated in writing with cache memories?

The data in main and cache memory can be written by processors or I/O devices. The major problems associated in writing with cache memories are:

a) The contents of cache and main memory can be changed by more than one device. For illustration CPU can write to caches and I/O module can directly write to main memory. This can result in inconsistency in values of main and cache memory.

b) In case of multiple CPUs with different cache a word changed in one cache automatically invalidates that specific word in other cache as well.

The proposed schemes for writing in system with caches are:

(a) Write through: Write the data in main memory as well as cache memory. The other CPUs - Cache combination has to watch with traffic to main memory and make appropriate modification in contents of cache. The drawback of this scheme is that a bottleneck is created because of large number of accesses to main memory by different CPUs.

 (b) Write block: In this technique updates are made only in cache, setting a bit known as Update bit. Only those blocks whose update bit is set is replaced in main memory. However here all accesses to main memory whether from other CPUs or I/O modules required from cache resulting in complex circuitry. 

 (c) Instruction Cache: An instruction cache is one that is used for accessing only instructions and nothing else. Benefit of such a cache is that as instructions don't change we do not need to write instruction cache back to memory unlike data storage cache.


Related Discussions:- Major problems associated in writing with cache memories

State in brief about polymorphism, State in brief about Polymorphism C...

State in brief about Polymorphism Class hierarchy is the deciding feature in the case of more than one implementation of properties. An object oriented program to compute the

Explain instruction stream and data stream, Instruction Stream and Data Str...

Instruction Stream and Data Stream The term 'stream' indicates to a series or flow of either instructions or data operated on by computer. In the entire cycle of instruction ex

Evaluation function - canonical genetic algorithm, Evaluation function - ca...

Evaluation function - canonical genetic algorithm: However note that this termination check may be related or the same as the evaluation function - that discussed later - but

Essential features of an algorithm, Necessary features of an algorithm: ...

Necessary features of an algorithm: 1.Input: The algorithm should take zero or more input. 2. Output: The algorithm should generate one or more outputs.  3. Definiteness:

What is the efi shell?, The EFI community has formed an open source shell e...

The EFI community has formed an open source shell environment. Rather than booting directly into a full OS, on some executions, the user can boot to the EFI shell. The shell is an

What is the main reason to encrypt a file, The main reason to encrypt a fil...

The main reason to encrypt a file is to ? Ans. The main purpose to encrypt a file is to secure that for transmission.

Speed up factor, Remember, the value of α is between 0 and 1. Now, let us p...

Remember, the value of α is between 0 and 1. Now, let us put some values of α and compute the speed up factor for increasing values of number of processors.  We get that the S(N) k

Principles of contract law, Andrew, a 17 zear old university student decide...

Andrew, a 17 zear old university student decided to hold a post exams party for his friends. Andrew asked Kath, a family friend and the owner of 'Kath's Katerers' to supply food

Basic need of random access memory, Q. Basic need of Random Access Memory? ...

Q. Basic need of Random Access Memory? Main memory is Random access memory. It is generally organised as words of fixed length. Length of a word is termed as word length. Every

Define a protocol when an error recovery develop for a link, Suppose you ha...

Suppose you have to develop an error recovery protocol for a link that is unreliable and delay sensitive, which of the following protocol would you choose? (i) Stop & wait.

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd