All computing is driven by one basic mandate: Go faster. It's easy to forget, when you're tuning SQL Server to optimize performance or fretting when it takes a few seconds longer than usual to open a file or retrieve a message, that everything depends on the processors inside the device containing data you're trying to access. Moore's Law—the well-known prediction attributed to Intel cofounder Gordon Moore that computing power doubles every 18 months—keeps us expecting faster and faster systems running ever more complex applications. Although it's uncertain how much longer the "law" will hold true, the advent of 64-bit dual-core processors, first released by AMD and Intel in April 2005, will help ensure that processing power continues to grow in a Moore-like way, at least for the foreseeable future.

In the year since AMD and Intel introduced their dual-core chips, dual-core has moved into the mainstream of business computing. Dual-core desktops, servers, and mobile-computing products are widely available. Benchmark test results for systems that use AMD or Intel dual-core processors show significant price and performance benefits, and real-world users are seeing improvements in speed and multitasking capability on their dual-core systems. If you've been considering a hardware upgrade and haven't yet bought a dual-core system, now's a good time to consider doing so. To help you evaluate the technology, we'll look at the basics of dual-core processors; currently available dual-core hardware; how Windows OSs, SQL Server 2005, and other Microsoft technologies benefit from dual-core technology; and what's on the horizon for dual-core in 2006.

Two Cores on One Die


As its name implies, a dual-core processor comprises two separate processors, typically placed side by side on a single silicon die, as Figure 1 shows.The performance gains of dual-core technology result from the way the two processors communicate with each other. On a dual-core system, each processor has its own cache, but the processors communicate via a shared pipeline—which can allow application instructions to execute more efficiently than on a single-core processor. In contrast, on a dual-processor, or multiprocessor, system, each CPU has its own cache, and the CPUs aren't directly connected. Because they're on a single chip, dual-core processors take up less space on a printed circuit board (PCB) than multiprocessors do. Dual-core processors also consume less power, generate less heat, and cost less than multiprocessor systems.

Dual-Core Vendors


AMD and Intel are the key vendors in the 64-bit dual-core arena, although IBM is currently producing its own POWER5 and PowerPC-based dual-core processors and Motorola is also developing dual-core technology. (IBM was the first computer manufacturer to produce a dual-core processor, the POWER4.) Most of the preeminent hardware vendors in the Microsoft world—HP, IBM, and Sun Microsystems—offer a variety of systems that use AMD or Intel dual-core technology. Dell, however, has stated publicly that it remains firmly committed to keeping its hardware "Intel Inside," and its dual-core systems contain only Intel processors—namely the Xeon or Pentium D dual-core processors.

AMD's first dual-core processor was its dual-core AMD Opteron, and IBM, HP, and Sun were the first vendors to offer Opteron-based servers and workstations. The Opteron is available in 2.0GHz, 2.2GHz, 2.4GHz, and 2.8GHz models. Since debuting the Opteron, AMD has also released the Athlon 64 and Athlon 64 X2, both for desktops and notebook computers, and the Turion 64 mobile-technology processor for notebooks.

AMD's dual-core effort is part of the company's overall x64 computing strategy, called AMD64. "We built AMD64 technology from the ground up for multicore processing," said Marty Seyer, corporate vice president and general manager for AMD's Microprocessor Business Unit, Computation Products Group. OEMs can upgrade their existing AMD64 platforms from single-core AMD64 processors to dual-core ones, he said.

Intel's primary dual-core processor is the 2.8GHz Xeon, which, like AMD's dual-core offerings, supports 64-bit computing. Intel also offers an entry-level dual-core processor, a 2.8GHz Pentium D.

Dual-Core's Price/Performance


Do dual-core systems really perform faster than single-core systems? And how does their price/performance stack up against single-core systems? As you might expect, systems based on AMD and Intel dual-core processors have been benchmarked by using the Transaction Processing Performance Council (TPC) TPC-C transaction-processing measurements. Recent TPC-C benchmark results favor a dual-core processor server—a Dell PowerEdge 2800 with Intel's 2.80GHz dual-core Xeon and running x64 versions of Windows Server 2003 and SQL Server 2005. The PowerEdge boasted the highest number of transactions per minute (tpmC)—38,622—and the best price/performance figure—$.99 per transaction—as compared with single-core processor machines, such as Dell's PowerEdge 2800 with a single-core 3.6GHz Xeon, at $1.29 per transaction, and HP's ProLiant ML350T03 with a single-core 3.0GHz Xeon, at $1.57 per transaction. Another set of benchmarking tests of multiprocessor systems favors a four-processor, eight-core server—the HP Proliant DL585 with AMD's Opteron 880 dual-core 2.4GHz processors and running x64 editions of Windows 2003 and SQL Server—over four-processor, single-core systems. (See the TPC Web site at http://www.tpc.org for the most current bench-marking results and to compare results for specific single- and dual-core systems.)

Users' experiences using dual-core machines tend to corroborate the benchmarking statistics, though perhaps less dramatically. Sixty-four bit versions of applications, such as x64 SQL Server 2005 and x64 Windows 2003, stand to benefit more from dual-core processors as compared with 32-bit applications because the 64-bit versions are designed to run under a 64-bit processor architecture. (Of course, 32-bit applications can run on dual-core systems and will see some performance benefit from doing so; they just can't address the full amount of memory or process the full 64 bits of data per clock cycle that a 64-bit application can.) Companies that make heavy demands on their databases or whose processes involve a lot of CPU-intensive computing—such as MySpace, a popular social-networking and music Web site, and Sabre Holdings, an airline reservations service—have experienced significant performance improvements, notably in their SQL Server 2005 applications, since moving to dual-core systems in tandem with a move to 64-bit applications.

Dual-Core and Microsoft Technologies


Upgrading to a dual-core server could increase your software-licensing costs, depending on the applications you're running on your server(s). Currently, many vendors license their software on a per-core basis. However, Microsoft licenses its server software on a per-processor basis; for licensing purposes, Microsoft treats a dual-core processor as one physical processor. So, for example, to run SQL Server 2005 on a server with one dual-core processor, you'd need one SQL Server 2005 license. One of Microsoft's main database competitors, IBM, also uses the per-processor licensing model, and another Microsoft database rival, Oracle, recently switched from per-core licensing to a licensing model that's a compromise between per-core and per-processor.

What's Ahead?


Virtualization—the ability to run multiple instances of an OS or application on the same hardware—is a hot technology, and AMD and Intel have stated their intention to enhance their dual-core processors to support virtualization. Both vendors are developing virtualization technologies that they predict will improve server utilization and enable dual- and single-core servers to run multiple, concurrent instances of OSs faster than before. Intel recently enabled the virtualization capability in its dual-core Xeon processor and is scheduled to ship its next-generation dual-core "Bensley" server processors with virtualization technology in the first half of 2006. AMD announced plans to enhance virtualization as well as security in its 64-bit processors and is expected to ship its dual-core processors with virtualization capabilities in March. Such virtualization-technology improvements at the processor level could also spur companies to consolidate their servers onto relatively fewer boxes.

2006 looks to be the year when 64-bit computing finally becomes a practical reality for Microsoft users as more sites move to x64 versions of Windows and SQL Server and evaluate the upcoming 64-bit Exchange 12 when it's released in beta this year. Servers based on dual-core technology will likely play an important role in helping 64-bit gain mindshare in the Windows world and convince more companies to make the transition to x64 platforms. So far this year, AMD and Intel have shown they intend to work hard to boost dual-core processors' presence in the market. In February, AMD cut prices dramatically—in some cases by more than 40 percent—on some of its dual-core server processors, while Intel announced rebates on three of its dual-core desktop processor models.

It's clear that AMD and Intel are committed to dual-core technology, and it's only a matter of time before hardware manufactures transition their customers to dual-core processor machines. Dual-core systems' impressive price/performance stats, ability to run both x32 and x64 applications, and lower associated costs (e.g., licensing) and power usage relative to multiprocessor systems provide compelling reasons for IT pros to consider upgrading to dual-core hardware.