Drilling into dual core
Published: 28 Sep 2005 17:25 BST
Hardware makers are now marketing servers based on a performance-per-watt measurement. Dell says its low-end PowerEdge 850 server, with a dual-core Pentium D, offers a 43 percent performance gain per watt, and HP has similar figures for its ProLiant DL585, a four-way, dual-core Opteron server.
On the desktop, the main benefit of the multi-core could be smaller, quieter systems along the lines of the Mac mini; indeed, a dual-core mobile chip from Intel is likely to power future versions of the Mac mini. Some analysts have gone so far as to predict the end of the tower unit, with its noisy cooling systems. Operations like media encoding will particularly benefit from dual-core.
The new dual-core world isn't without its hitches. For one thing, not all software benefits equally from the presence of two cores, a fact companies should keep in mind when buying new systems. Software needs to be able to take advantage of multiprocessing and multithreading to fully benefit. "Enterprise platforms are highly threaded today and, as such, we expect that they will be able to take great advantage of the compute capability provided with dual-core and multicore," says Jeff Austin of Intel's product marketing group.
Transaction processing, databases, scientific applications and media encoding are among the types of software that should show significant performance gains. Desktop productivity software won't really benefit, since it doesn't need much performance in the first place. Some classes of software, like gaming, will actually take a performance hit, according to chipmaker benchmarks.
The initial dual-core designs, particularly Intel's, will need significantly more development before they can take full advantage of the efficiencies of dual-core. "Intel cobbled together its dual-core plan at the last minute. That's why Intel's dual core-chips so far are just two independent chips that haven't been cut apart," says Glaskowsky. "That approach leads to large amounts of redundant logic."
Because current Intel and AMD chips are designed to fit into a single existing socket, both cores are connected to the same power supply, Glaskowsky pointed out. That means a single core can't be put to sleep — thus conserving power — unless both cores are idle. Dual-core server chips on the way from Intel and AMD will continue to use two separate memory caches for each core, a less efficient approach, but one that simplifies the design work.
It will be some time before chipmakers have fully adjusted to a multicore world, Glaskowsky says: "In the long run both AMD and Intel will provide more sophisticated multi-core designs that will solve all of these problems, but it will take a few years to get there."
Hardware aside, the new chips are leading software vendors to re-evaluate the way they license their products, which could mean sudden increases in some companies' software costs. Hardware makers don't agree, but such increases may be justified, considering that buyers are practically getting two processors for the price of one.
It's a mistake to stick to old, obsolete ways of thinking about hardware performance, Glaskowsky believes. "Multicore technology may finally force users and software vendors to look at overall performance, not specific implementation details," he says. "They adapted to multiprocessing years ago, but more recently, basically ignored multithreading. AMD and Intel would like everyone to ignore multicore technology, but that won't happen."
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