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One of the nice feature of windows 7 for low memory system is ReadyBoost, a software component that uses flash memory as a cache to actually speed up the the performance(Ref-Wikipedia).

But If we take computer architecture as a whole into consideration, we have cache levels(L1, L2 etc) located in between processor and RAM. So If we use flash memory as a cache then where it actually resides in this hardware hierarchy and how the data or control flow takes place?

In simple words, my question is, does ReadyBoost actually extends the system cache level by exploiting the use of flash memory or does it extends the performance of RAM? Or Does it serve as a disk cache sitting in between RAM and HDD?

Anybody please explain me. Thanks.

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migrated from Feb 17 '14 at 20:17

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I have to imagine that it would occupy its own level in the memory hierarchy, and its position would be determined by its access speed - read, most likely. Without knowing anything about it, I'd wildly guess that it sits just above the HDD's pagefile. Not sure whether/how this addresses your question. Also, how do you imagine the performance of RAM could be extended, if not by using cache? – Patrick87 Feb 17 '14 at 19:29
My guess is that it adds another hierarchy element between RAM and HDD. Given the typical speeds of flash storage (slower than RAM) there is probably little sense to using it at cache (or even RAM) level. – Raphael Feb 17 '14 at 21:32
@Patrick87 If it sits just above the HDD's page file, but they said that this caching applies to all disk content, not just the page file or system DLLs(Ref-Wikipedia). And RAM performance increases in the sense that, it might implement multi-channel data transfer if we use this extra flash memory. – Winn Feb 18 '14 at 3:10
@Raphael Do you mean it is kind of a disk cache? Well, my experience of using ReadyBoost on my 1GB, 1.73GHz system says that it produces a significant performance improvement especially while reading and accessing filesystem. – Winn Feb 18 '14 at 3:17

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