Slashdot Mirror
Remote Direct Memory Access Over IP
doormat writes "Accessing another computer's memory over the internet? It might not be that far off. Sounds like a great tool for clustering, especially considering that the new motherboards have gigabit ethernet and a link directly to the northbridge/MCH."
I tried something like this a while ago -- I wanted to mount an NFS-exported file via loopback and use it as swap.
The file in question actually resided in a RAM drive on another machine on the LAN.
I couldn't get it to work in the 45 minutes or so I messed around with it. I'm not sure if Linux was unhappy using an NFS-hosted file for swap, or what exactly the problem was, but I did get some funny looks from people to whom I explained the idea (ie, to determine whether the network would be faster than waiting for my disk-based swap).
Of course, this was back when RAM wasn't cheap...
Somebody get that guy an ambulance!
Um... easier said than done there, hotshot.
When a program asks for memory there's a reasonable amount of loops it has to go through in the processor to get the memory, because the processor manages memory. Making a program that toys with memory over the internet wouldn't be slightly exciting.
DMA channels let something, usually a video card, sound card, IDE bus, etc. do what it needs to do with the system's memory without bothering the processor. The speed gained by not bothering the processor when accessing memory is what makes UltraDMA hard drives so fast, video cards accelerated (in addition to a lot of other l337 tricks), etc.
Now, you take a cluster, connected via gigabit network, in which each computer can directly access each other's memory as opposed to using a program to do it that just takes the target processor's cycles. THAT is slightly exciting.