Thread: Nehalem processor

The Nehalem based Xeon processor -Xeon 5500 Series is the first processor from Intel to have Native Quad Core support. We received a 1 U rack server from Intel with two 2.9 GHz Nehalem processors and 24GB RAM. We ran quite a few tests on it. and as expected, the results were mind boggling. We will discuss the results later. First. let's take a quick look at some of the key features of the processor. The basic features are pretty much similar to the Core i 7 desktop architecture and offer the following functionalities:

Native quad-core
Till now. all previous Xeon processors with more than two cores were built using multi-chip modules of dual core processors. So they were essentially two orthree dual cores modules fixed in one chip creating quad or hex core CPUs. With Xeon 5500 series. there is native quad c,1:Jre design. This is similar to AMD's Phenom X4 CPUs. The same feature is also available with Intel's Nehalem based desktop processors, the 'Core i 7'.

The advantages of having a native quad-core over an MCM (Multi core modules) aresignificant in terms of processor energy efficiency. performance, and dynamic scalability. We will see some of these in our benchmark results.



Inclusive level 3 cache
First showcased on earlier Xeon server chips and then on desktop Core i7 CPUs, the Xeon 5500 family of CPUs feature up to a massive 8MB of level 3 cache (shared between all four cores) as compared to 2 MB of Phenom X4. The cache is also described as an inclusive level 3 cache. Intel claims. an inclusive cache is more efficient than an 'exclusive' cache design, even if it does mean that 1MB of Nehalem's 8MB Level 3 cache is taken up by storing a copy of the 256 KB Level 2 cache inside each processing core.

Integrated memory controller
By modularizing the design of the CPU and the orthbridge. the memory controller has been brought to the Nehalem CPU die. The separate processing cores and caches are linked to the on board memory controller via a new bus standard called the QuickPath interconnect, replacing the conventional front side bus. As QuickPath replaces the Front side Bus (FSB). it also takes over the role of allowing the CPU to connect to other system components. buses and controllers such as the PCI Express controller and DDR3 memory, reducing latency and improving performance considerably.

Hyper- threading
Another feature worth mentioning is Hyper-threading. Using spare resources of a core to execute a second process thread. Hyper-threading enables a quad-core Nehalem processor to accept and process eight threads simultaneously. making it even more massively parallel and powerful than the current Core 2 Quad CPUs.