Multiplying your power
- By Dan Carney
- Oct 17, 1999
Employing additional processors may seem like an obvious solution to those seeking to boost PC productivity, but getting real benefits from multiprocessing has proved to be difficult for vendors of machines that use Intel Corp.-based chips.
Because of some unfortunate twists on "new math" that occur when processors are wired together to share work, users often have found that four processors working in tandem does not provide four times the computing power of a single processor.
But recent improvements by Intel have made processors more efficient at cooperating in groups as large as eight. And Microsoft Corp.'s popular Windows NT operating system also has improved in this regard, with Windows 2000 expected to make the multiplication of processors even more linear.
"In the server space, the action is all around multiprocessing," said Joe Barker, vice president of Gartner Group Inc., Stamford, Conn. "Intel's processors keep getting faster, so there is very little advantage of [reduced instruction-set computing architectures] over Intel processors."
Tests on Windows NT servers using Pentium III Xeon chips show that when the number of processors is doubled from two to four, processing power increases by a factor of 1.9, according to Intel. Though not double the speed, it is much closer than in the past. And when the processors were doubled again, the power increased by a factor of 1.6 to 1.7.
Intel says this number will improve with the release of Windows 2000.
"Windows 2000 will be a driver of multiprocessing," said Jim Gargen, IBM's director of product marketing for Netfinity servers. "It has better driver support and better scaling to more processors."
Barker estimated that 80 percent of new Intel servers run Windows NT. But the Linux operating system has been receiving significant interest among federal agencies accustomed to working with Unix on RISC multiprocessors. Linux provides the first widely popular open version of Unix for Intel-based computers, making federal Unix programmers feel at home when working on Intel systems. And like Windows 2000, Linux works well with multiprocessors.
"We are seeing good scalability for Linux across our product line," Gargen said.
Because of those changes in processors and operating systems, PC makers that previously built mostly uniprocessor workstations and dual-processor servers are switching to dual-processor workstations and eight-way servers.
These high-powered machines should garner wide interest among federal customers because their prices will be much lower than past multiprocessors. This is partly because of the ever-declining price of many PC components. But it is also because earlier Intel processors and chipsets left multiprocessing up to the PC vendor's ingenuity. Now those capabilities are built in, so vendors don't have to develop costly custom circuits to trick processors into working together.
Mark Bony, product manager for Hewlett-Packard Co.'s Kayak workstation family, said he expects business users and technical users to purchase the new and more affordable dual-processor workstations. In fact, HP is making dual-processor capability standard on all of its Kayak workstations, although the less expensive ones will not have the optional second chip installed.
In workstation applications, which were typically run in uniprocessor environments, the addition of a second chip not only improves performance but can make the machine more reliable.
"One of the biggest benefits is system stability," Bony said. "The system doesn't crash as often."
Federal agencies that need even more power from their multiprocessor workstations link them together using clustering technology, similar to the technique that made Digital Equipment Corp. VAX minicomputers popular in the 1980s. Rob Crawford, workstation brand manager for Dell Federal, said those techniques have enabled agencies to obtain "supercomputer performance from a bunch of Intel processors."
Crawford may be exaggerating, but his point is well taken. Clustered PCs may not equal the performance of a supercomputer, but they are about halfway there. And they certainly are more accessible and much cheaper.
The numerical modeling group at the Energy Department's Stanford Linear Accelerator Center runs its modeling software on an expensive Cray supercomputer, said team leader Kwok Ko. But it is difficult to get time on the Cray, so when they want to test new software, programmers can run it on clustered Dell multiprocessor workstations.
"The cluster provides us with something between the supercomputer and a workstation," Ko said. "It is a very cost-effective way of providing a computing resource in the medium range."With 32 of the workstations—about $70,000 worth—hooked together, they are about half as powerful as the $30 million Cray, he said.
Randy Melen, high-performance team leader at the center, said using Dell Intel-based multiprocessing workstations has been one-third to one-half less expensive than using the least costly RISC/Unix hardware.
Even federal office workers can benefit from the increased speed of dual-processor workstations because more "multithreaded" applications—applications that can break its tasks into pieces, or threads—are being written for Windows, that can be processed separately. Personal productivity stalwart Office 2000 is multithreaded so that users can run other applications while processing a large print job, for example.
Adobe PhotoShop and popular computer-aided design applications also are multithreaded, so a wide variety of federal users would benefit from an increased processing speed that multiprocessing can offer, Bony said.
In servers, Intel has slowly progressed from single to dual to four-way processors. Intel then developed the Pentium Pro chip, which was designed for four-way multiprocessing. Next was the desktop-oriented Pentium II chip, and it was capable of dual processing.
But the Pentium III Xeon was designed with serious multiprocessing in mind. And a new chipset released in September, code-named Profusion, enables vendors to cram as many as eight Pentium III Xeon chips into a server.
Vendors that design specialized components offer machines with as many as 64 chips wired together for mainframe and supercomputer-class systems, said Pat Buddenbaum, marketing manager of Intel's server component division.
For mainstream servers, eight is now the limit. Intel plans to apply its usual tricks of shrinking the circuit size to reduce power consumption and the resulting heat output. That means future chips will rev to higher clock rates when newer designs become available.
The new multiprocessing servers dramatically undercut some traditional servers in price/performance, said Shaf Mohebbi, president of V Squared Inc., a Dulles, Va., server manufacturer that provides equipment to federal resellers and integrators. For example, an Intel-based multiprocessor server can churn through 40,000 transactions per minute (TPM), for a price of $18 per TPM, Mohebbi said. Compaq's Alpha costs $79 per TPM, Hewlett-Packard's RISC servers cost $88 per TPM and Sun Microsystems Inc.'s servers cost $76 per TPM, he said.
Mohebbi said federal customers can save money running those machines because the lower price enables customers to buy more powerful servers that can combine the work of several servers into one. Fewer servers doing the same work means lower management costs. "It makes management, back-up and support of the servers easier," he said.
"One of the biggest trends now is the concept of server consolidation," said Brad Day, senior analyst at Giga Information Group Inc., Cambridge, Mass. "It is the physical consolidation of a lot of dispersed one- and two-way servers on one eight-way server."
The goal is reduced maintenance that enables federal agencies to cut personnel costs. "You're going to see anywhere from 30 percent to 50 percent staff savings, just from system management," Day said.Having an agency's servers running Windows on Intel hardware also saves money, according to Mike Edwards, a member of the architecture and integration team for the Army Recruiting Information Support System (ARISS) at Fort Knox, Ky. That is because they can be maintained by the same staff members who look after the Windows-based PCs."We only need one administrator skill set from top to bottom," he said. "Unix administrators don't come cheap."The ARISS program provides database server support to the Army's 14,000 mobile recruiters. The Army uses two- and four-way 500 MHz Pentium III-equipped Dell servers for ARISS. The Army doesn't need the power of eight-way servers yet, but it looks like an attractive option for the future, Edwards said. "It appears to us that [Intel servers] will scale nicely to eight processors," he said.
High-performance multiprocessors will never be generic commodities, but increasing performance at lower prices will challenge vendors to find ways to differentiate their products for federal customers, said Phil Kennett, vice president of sales for Gateway Federal.
Two features that federal agencies like in multiprocessor systems are rack mountability and shared disk storage, Kennett said. Rack mounting is necessary in many mobile applications for use on ships, aircraft and in vans, he said. Such servers take up less space and are more durable when rigidly mounted in their racks. The ability for servers to share disk arrays also conserves space, Kennett said.
-- Carney is a free-lance writer based in Herndon, Va.