Xeon Phi was a series of x86 manycore processors designed and made by Intel. It was intended for use in supercomputers, servers, and high-end workstations. Its architecture allowed use of standard programming languages and application programming interfaces (APIs) such as OpenMP.
Xeon Phi launched in 2010. Since it was originally based on an earlier GPU design (codenamed "Larrabee") by Intel that was cancelled in 2009, it shared application areas with GPUs. The main difference between Xeon Phi and a GPGPU like Nvidia Tesla was that Xeon Phi, with an x86-compatible core, could, with less modification, run software that was originally targeted to a standard x86 CPU.
Initially in the form of PCIe-based add-on cards, a second-generation product, codenamed Knights Landing, was announced in June 2013. These second-generation chips could be used as a standalone CPU, rather than just as an add-in card.
In June 2013, the Tianhe-2 supercomputer at the National Supercomputer Center in Guangzhou (NSCC-GZ) was announced as the world's fastest supercomputer (, it is ). It used Intel Xeon Phi coprocessors and Ivy Bridge-EP Xeon processors to achieve 33.86 petaFLOPS.
The Xeon Phi product line directly competed with Nvidia's Tesla and AMD Radeon Instinct lines of deep learning and GPGPU cards. It was discontinued due to a lack of demand and Intel's problems with its 10nm node.
History
Background
The Larrabee microarchitecture (in development since 2006) introduced very wide (512-bit) SIMD units to a x86 architecture based processor design, extended to a cache-coherent multiprocessor system connected via a ring bus to memory; each core was capable of four-way multithreading. Due to the design being intended for GPU as well as general purpose computing, the Larrabee chips also included specialised hardware for texture sampling. The project to produce a retail GPU product directly from the Larrabee research project was terminated in May 2010.
Another contemporary Intel research project implementing x86 architecture on a many-multicore processor was the 'Single-chip Cloud Computer' (prototype introduced 2009), a design mimicking a cloud computing computer datacentre on a single chip with multiple independent cores: the prototype design included 48 cores per chip with hardware support for selective frequency and voltage control of cores to maximize energy efficiency, and incorporated a mesh network for inter-chip messaging. The design lacked cache-coherent cores and focused on principles that would allow the design to scale to many more cores.
The Teraflops Research Chip (prototype unveiled 2007) is an experimental 80-core chip with two floating-point units per core, implementing a 96-bit VLIW architecture instead of the x86 architecture. The project investigated intercore communication methods, per-chip power management, and achieved 1.01 TFLOPS at 3.16 GHz consuming 62 W of power.
Knights Ferry
Intel's Many Integrated Core (MIC) prototype board, named Knights Ferry, incorporating a processor codenamed Aubrey Isle was announced 31 May 2010. The product was stated to be a derivative of the Larrabee project and other Intel research including the Single-chip Cloud Computer.
The development product was offered as a PCIe card with 32 in-order cores at up to 1.2 GHz with four threads per core, 2 GB GDDR5 memory, and 8 MB coherent L2 cache (256 KB per core with 32 KB L1 cache), and a power requirement of ~300 W, built at a 45 nm process. In the Aubrey Isle core a 1,024-bit ring bus (512-bit bi-directional) connects processors to main memory. Single-board performance has exceeded 750 GFLOPS. The prototype boards only support single-precision floating-point instructions.
Initial developers included CERN, Korea Institute of Science and Technology Information (KISTI) and Leibniz Supercomputing Centre. Hardware vendors for prototype boards included IBM, SGI, HP, Dell and others.
Knights Corner
The Knights Corner product line is made at a 22 nm process size, using Intel's Tri-gate technology with more than 50 cores per chip, and is Intel's first many-cores commercial product.
In June 2011, SGI announced a partnership with Intel to use the MIC architecture in its high-performance computing products. In September 2011, it was announced that the Texas Advanced Computing Center (TACC) will use Knights Corner cards in their 10-petaFLOPS "Stampede" supercomputer, providing 8 petaFLOPS of compute power. According to "Stampede: A Comprehensive Petascale Computing Environment" the "second-generation Intel (Knights Landing) MICs will be added when they become available, increasing Stampede's aggregate peak performance to at least 15 PetaFLOPS."