News

posted on 24 March 2008 11:01

Sun  has won a 5-year DARPA research grant to develop guided light communications between CPU chips which, contrary to current practise, will not be cut out and separated from other chips but will be on some substrate with wave-guided light facilitating blindingly fast inter-chip communications.

The inter-chip switching technology is called Silicon Photonics and IBM, Intel and NEC are also active in the area. It could enable computer chips or cores to work for much more of the time flat out instead of being constantly interrupted by I/O waits.

This could bring supercomputer performance to servers with teraflop levels of power becoming feasible. (Intel Terraflops wafer pictured.)

A downstream problem needs to be solved though. CPUs get data from RAM and the current balance between RAM bandwidth and CPU capacity will be disrupted as the light-interlinked CPUs suck data out of RAM like a vacuum pump on steroids and then stuff it back in like a fire hose trying to fill a bath.

The DRAM-CPU link will need radical re-thinking. Perhaps it will need parallelism built in or even light-based DRAM-CPU complex communications. A side-effect will be a great jump in memory capacity; we'll really need the 64-bit addressing that we have available.

If the technologists and engineers pull off this trick and make light work of inter-CPU communication as well as significant increasing CPU-DRAM bandwidth then we won't see radically faster processors hobbled by slow storage.

Instead Moore's Law will have been side-stepped and we can look forward to very much faster servers and PCs. (They might even deal with Vista bloat.)

^{[Paul Roberts, news editor.]}