Intel has revealed new details about the firm’s next-generation CPU microarchitecture, code-named Nehalem. It is on track for delivery in the second half of 2008. In fact, hereported that each chip will be comprised of approximately 731 million transistors.
In its “largest configuration,” Nehalem will pack eight CPU cores onto a single die. Each of those cores will present the system with two logical processors and be able to execute two threads via simultaneous multithreading (SMT)—a la HyperThreading. So a single Nehalem chip will be able to execute 16 threads at once. In terms of numbers, this means a power gradient of 10-25 percent for single-threaded applications, and between 20 and 100 percent for multi-threaded applications. Nehalem will integrate a high-performance memory controller and a new chip-to-chip interconnect known as QuickPath—both provisions similar to AMD’s Opteron processors.
Here are some new initial disclosures around Nehalem microarchitecture:
* Dynamically scalable for leadership performance on demand with energy efficiency
o Dynamically managed cores, threads, cache, interfaces and power
o Leverages leading 4 instruction issue Intel® Core microarchitecture technology
o Simultaneous multi-threading (similar to Intel Hyper-Threading Technology) returns to enhance performance and energy efficiency
o Innovative new Intel® SSE4 and ATA instruction set architecture additions
o Superior multi-level shared cache leverages Intel® Smart Cache technology
o Leadership system and memory bandwidth
o Performance enhanced dynamic power management
* Design scalable for optimal price/performance/energy efficiency in each market segment
o New system architecture for next-generation Intel processors and platforms
o Scalable performance: 1 to 16+ threads, 1 to 8+ cores, scalable cache sizes
o Scalable and configurable system interconnects and integrated memory controllers
o High performance integrated graphics engine for client
Unlike Penryn, which is a shrink/derivative of Core 2 Duo (Merom), Nehalem is architected from the ground up for 45nm. This is a major new design, and there is some truly tantalizing details about it. Nehalem has its roots in the four-issue Core 2 Duo architecture, but the direction that it will take Intel is apparent that is that Nehalem is not only designed to take Intel up to eight cores on a single die, but those cores are meant to be mixed and matched with varied amounts of cache and different features in order to produce processors that are tailored to specific market segments.
The blockbuster revelation is that some Nehalem designs will sport an on-die memory controller and integrated graphics processor. Is there would be a GPU integrated onto the actual die along with the general-purpose CPU cores? The answer is that the GPU would be “in the socket” with the CPU or in other term Intel will almost certainly be using its packaging skills to put a GPU in the same package as a Nehalem CPU. Furthermore, this is going to help out with mobile products, small-form-factor devices, and anywhere else that power and cooling are more critical than raw performance. It is expected that such CPU/GPU devices will cut down on the number of on-die cores that you can put on the CPU die (for power dissipation reasons). A Nehalem CPU/GPU combination is expected to consist of a dual-core Nehalem CPU that sports an on-die memory controller, with a GPU sandwiched in the same package with it. This will be a killer mobile part in terms of performance per watt.
As far as the on-die memory controller, this has been a long time coming for Intel. Intel is saying that not every Nehalem part will necessarily have an integrated memory controller—they’ll tweak the number of cores and the on-die components to fit certain performance-per-watt targets for certain segments. The other big revelation is that Nehalem will bring back simultaneous multithreading to Intel’s processor line. Since the Pentium Pro (in 1995) Nehalem has the most significant new architectural changes. It is highly scalable with different components for different tasks. According to Intel it will have 1 through 8+ cores and integrated memory controllers for DDR3 SDRAM with 1 to 4 memory channels. Nehalem will also utilize the new point-to-point processor interconnect, that is the Intel QuickPath Interconnect, replacing the legacy front side bus. This processor will be launched in both native quad core and octo core.”native” here means the configuration with all the cores situated on single silicon die. Quad core is known to have 731 million transistors and unknown amount of L2 cache. As for Nehalem processors with additional features such as GPUs, there will be two separate dies that is one with the cores and another one will have the additional features.
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