Write-through and Write-back cache

[Klaty]

I am engineering student, i went for any interview and over there the interviewer asked me a question i.e "Explain what is the difference between write through and write back cache?". And i was unable to answer this. Please somebody can answer regarding this Intel motherboard question.

[Amd Athlon]

I think in the write-through cache, the contrast changes made to cached data are simultaneously made in the original copy, whereas in write-back not. The write back cache are able to perform more quickly/faster compare to the write through cache. But in some points, the differences between cached and original data could lead to problems, and so, write through caches should be used. Hope your problem is fix.

[PeterAGASSI]

Write-Through cache: In this, once the writing is done in the cache memory, the main memory is updated too immediately to maintain the reliability.
Write-Back cache: In this, once the writing is done in the cache memory, a flag bit known as dirty bit is set. And when this value is required it is replace by that bit check, and if it is set then the value is taken to main memory. Hope you will understand the term write-through and write-back cache.

[Joshua]

To me also same question was asked during interview and my answer was somewhat like: According to me, this both(i.e writethrough and writeback) are the cache write hit policy,
->Write-through: In this, the information is written to the both the side of the cache and the main memory upon a hit.
->Write-back: In this, the information is written to the cache only, and the main memory is updated upon a read miss.
After this answer by me, the interviewer selected me, so i think this perfect answer for interview purpose. All the best.

[Russell]

The differences between the Write-through and Write-back cache can be based on 2 factors (i.e Performance and Integrity of Data). The write-through has a better integrity and it will also flush for each writes. The write-back will hold up the write till the same cache line has to be used up for a read. Thus, write-back will proivde good performance, as it save many memory write cycles /write and write-through does not provides like this performance.

[MattyBoy]

My personally thinking says that the write-through policy is mostly slower, but offers advantage of coherence between cache and main memory. And whereas when we come to write-back, we say it is faster and frequently used. It also make use of the Dirty bit. If the data in cache is not in coherence with one in main memory, then the Dirty bit is set. Write Through doesn't provide the performance compared to which provided by Write-Back. Hope your problem will be fixed.