Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
Probably a stupid question for most that know DMA and caches… I just know cache stores memory to somewhere closer to where you can access so you don’t have to spend as much time for the I/O.
But what about DMA? It lets you access that main memory with less delay?
Could someone explain the differences, both, or why I’m just confused?
I agree fully with the first answer, and there are some common additions…
On most DMA hardwares you can also set it up to do memory to memory transfers – there are not always external devices involved. Also depending on the system you may or may not need to sync the CPU-cache in software before (or after the transfer), since the data the DMA transfers into/from memory may be done without the knowledge of the CPU-cache.
The benefit of doing any DMA is that the CPU(s) is/are able to do other things simultaneously.
Of course when the CPU also needs to access the memory, only one can gain access and the other must wait.
Mem to mem DMA is often used in embedded systems to increase performance, or may be vital to be able to access some parts of the memory at all.
To answer the question, DMA and CPU-cache are totally different things and not comparable.