syn_anandtech: The Larrabee Chapter Closes: Intel's Final Xeon Phi Processors Now in EOL

The Larrabee Chapter Closes: Intel's Final Xeon Phi Processors Now in EOL

Intel this week initiated its product discontinuance plan for its remaining Xeon Phi 7200-series processors codenamed Knights Mill (KML), bringing an end to the family of processors that have now been superceded by the likes of Intel's 56-core Xeon Platinum 9200 family. Xeon Phi parts have been used primarily by supercomputers during its lifetime.

Customers interested in final Intel Xeon Phi 7295, 7285 and 7235 processors will have to place their final orders on these devices by August 9, 2019. Intel will ship the final Xeon Phi CPUs by July 31, 2020. Intel’s Knights Mill processors feature 64, 68, or 72 upgraded Silvermont x86 cores paired with AVX-512 units and MCDRAM. The parts were essentially Knights Landing parts optimized for Deep Learning applications.

Intel launched several generations of Xeon Phi over the years, including Knights Ferry, Knights Corner, Knights Landing, Knights Hill (never released), and Knights Mill. The product started off as the Larrabee project, aimed at designing a general purpose x86 compute graphics solution for Intel. We had a first glimpse of the initial architecture way back in 2008, however the graphics part of the project was killed by mid 2010, and the product lived on as a many-core processor with large vector compute units.

April 2007: Intel Developer Forum - Beijing 2007: Penryn and Intel's High End GPU
March 2008: Opening the Kimono: Intel Details Nehalem and Tempts with Larrabee
August 2008: Intel's Larrabee Architecture Disclosure: A Calculated First Move
September 2009: IDF 2009 - World's First Larrabee Demo
December 2009: Intel Cancels Larrabee Retail Products, Larrabee Project Lives On
May 2010: Intel Kills Larrabee GPU, Will Not Bring a Discrete Graphics Product to Market
June 2010: Intel MIC: 22nm, 50+ Cores, Larrabee for HPC Announced

In 2016, one of the original developers of Larrabee, Tom Forsyth, wrote an piece detailing the project, some of its goals, and how far the part had been developed with graphics in mind, before being released as a many-core processor. Here's a quote, and it's well worth a read.

From Tom Forsyth: Why Didn't Larrabee Fail?

PRIMARY GOAL: VIRTUAL SUCCESS! It would have been a real success if it had ever shipped. Larrabee ran Compute Shaders and OpenCL very well - in many cases better (in flops/watt) than rival GPUs, and because it ran the other graphical bits of DirectX and OpenGL pretty well, if you were using graphics APIs mainly for compute, it was a compelling package. Unfortunately when the "we don't do graphics anymore" orders came down from on high, all that got thrown in the trash with the rest. It did also kickstart the development of a host of GPGPU-like programming models such as ISPC and CILK Plus, and those survive and are doing well.

AVX-512 Support Propogation by Various Intel CPUs Newer uArch supports older uArch
	Xeon	General	Xeon Phi
Skylake-SP	AVX512BW AVX512DQ AVX512VL	AVX512F AVX512CD	AVX512ER AVX512PF	Knights Landing
Cannon Lake	AVX512VBMI AVX512IFMA		AVX512_4FMAPS AVX512_4VNNIW	Knights Mill
Cascade Lake-SP	AVX512_VNNI
Cooper Lake	AVX512_BF16
Ice Lake	AVX512_VNNI AVX512_VBMI2 AVX512_BITALG AVX512+VAES AVX512+GFNI AVX512+VPCLMULQDQ (not BF16)	AVX512_VPOPCNTDQ
Source: Intel Architecture Instruction Set Extensions and Future Features Programming Reference (pages 16)

As for the Xeon Phi family, Knights Mill was the last product. Last year Intel discontinued its Xeon Phi 7210, 7210F, 7230, 7230F, 7250, 7250F, 7290, and 7290F processors, known as Knights Landing. The final shipments of Knights Landing for old systems will be made by July 19, 2019, with Knights Mill on July 31, 2020.

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