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Rethinking Computer Design For an Optical World
holy_calamity writes "Technology Review looks at how some traditions of computer architecture are up for grabs with the arrival of optical interconnects like Intel's 50Gbps link unveiled last week. The extra speed makes it possible to consider moving a server's RAM a few feet from its CPUs to aid cooling and moving memory and computational power to peripherals like laptop docks and monitors."
moving memory and computational power to peripherals like ... monitors.
They mean ever more complicated DRM. Like sending the raw stream to the monitor to be decoded there.
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
Without factoring in speed of light drops due to index of refraction changes, at a distance of 1 meter you're looking at latencies of 7 nanoseconds just for travel time. The bandwidth may be decent but the latency is going to be an issue for any significant distance.
It would allow you to use components an a more modular way, especially around an office. If you're not big enough (of a company) to have dedicated rendering/encoding servers, you could move the GPU around depending on who's currently doing the work that requires it. Even on a more casual basis, you could have a bunch of laptops with mid-range GPUs, and have an external GPU for whomever if gaming at the moment. Just like people take turns in a household with the home-theater rig in the living room -- you don't need to install a huge LCD + amp + speaker system in every room, you just need to take turns.
Entomologically speaking, the spider is not a bug, it's a feature.
By my understanding, it's not so much the travel time as the decoding/switching/other electronic time. As one example, consider the switching time of a transistor/photodetector. The gate must collect enough energy to switch from "off" to "on". Increased speed means having fewer electrons enter the gate. Higher energy per electron means raising the voltage. That's why overclocking often involves fiddling with voltages. Unfortunately, with more voltage comes more induction, breakdown, and other headaches I don't know enough about to list.
In contrast, light is much simpler to work with. You can make a light beam brighter without affecting other beams much. There's little chance of a beam breaking through its cable. We can send higher energies to gates with ease. Higher energy means less time to switch, and faster operation.
Note that I am not a physicist, and not much of an electrical engineer. I may be entirely wrong.
You do not have a moral or legal right to do absolutely anything you want.
CPUs have high speed cache that is faster than the mainboard RAM for high speed processing on a set of data, and swap the cache to/from RAM as necessary (kind of like how you page RAM to your hard drive when you run out of RAM).
Such a small cache would be useless for GPUs though, so they need faster RAM to read the massive amounts of texture/vertex/shader/whatever data they have as quick as possible. They also benefit more from stuff like RAM that is optimised for high sequential read speeds, so it does make sense to use RAM that has been specially designed for GPUs if you actually care about graphics performance (I doubt most Mac Mini users do).
which is totally what she said
You people are not thinking nearly creative enough. The article doesn't make it clear why you'd want to move your memory farther away -- it would increase latency, yeah, but moreover, what are you going to put that close to the CPU? There isn't anything else competing for the space.
Here's a more interesting idea than just "outboard RAM": what if you replaced the RAM on a blade with a smaller but faster bank of cache memory, and for bulk memory had a giant federated memory bank that was shared by all the blades in an enclosure?
Think multi-hundred-CPU, modular, commodity servers instead of clusters.
Think taking two commodity servers, plugging their optical buses together, and getting something that behaves like a single machine with twice the resources. Seamless clustering handled at the hardware level, like SLI for computing instead of video if you want to make that analogy.
Minor complaint, the summary is a little misleading with units: they're advertising not 50 gigabits/s, but 50 gigabytes/s. Current i7 architectures already have substantially more memory bandwidth than this to local RAM, so the advantage is definitely communication distance here, not speed.
Most people don't want to mess around inside a computer case, just like most people don't want to mess with the engine of their car or truck, or with the insides of their televisions, etc.
Such a modular system would be similar to huge LEGO bricks, nothing to open up, just connect the bricks together. Hopefully they would make the modules in standard sizes and allow multiples of that standard size. A CPU module could be 2x2x2 units, optical drives could be 2x1x2, etc.
The system could allow to connect to at least four faces, so we don't end with with very tall or very wide stacks. Proper ventilation would be part of the standard unit size (you need more heatsinking than the aluminium casing allows? Make your product one unit bigger and put ventilation holes in the empty space). A standard material such as aluminium could be used so that machining/extruding could be used and would allow the modules to dissipate heat.