Zen (microarchitecture)

Zen

Zen's introductory slide, showing major changes
Produced 2016
Designed by AMD
Common manufacturer(s)
Instruction set AMD64 (x86-64)
Cores
  • 2 (essential)
  • 2–4 (mainstream)
  • 8–16 (enthusiast)[3][4]
  • 32 (server)[5][6]
Created 2012–2016
Transistors 14 nm (FinFET)[7]
Socket(s)
Predecessor Excavator
Successor Zen+[9]
Application Desktop, laptop, server

Zen is the codename for an upcoming computer processor microarchitecture from AMD,[10] expected for release in October 2016.[11] Designed from scratch rather than being an overhaul of AMD's long-standing Bulldozer architecture, the 14 nm architecture and its new AM4 socket will be the basis of the upcoming generation of AMD's high-end CPUs codenamed "Summit Ridge" starting in late 2016, and of future generations of APUs and Opteron server processors.

While the forthcoming series of "Bristol Ridge" APUs, expected in mid-2016, will be one last iteration of the Bulldozer architecture, it will already utilize the AM4 socket, embracing DDR4 support.[12] With the creation of Zen, the differences and issues present with previous sockets were removed due to Zen being more SoC-like in nature, making it possible to integrate a wide array of components and controllers that would previously differentiate sockets into the processors themselves, removing the need for different types of motherboards and sockets to support them and instead allowing Zen chips to be unified under a single AM4 socket.[13]

Architecture summary

According to AMD, Zen's main focus will be on increasing per-core performance.[14][15][16] A 2016 presentation from CERN engineer Liviu Valsan reported that the process would use SMT (Symmetric Multithreading) microarchitecture .[17] (see also Simultaneous multithreading) The change from a clustered multi-thread (CMT) design in the previous Bulldozer microarchitecture) to SMT is expected to offer higher per thread floating point performance at cost of lower core count/higher the die size.[16]

“ This is the first time in a very long time that we engineers have been given the total freedom to build a processor from scratch and do the best we can do. It is a multi-year project with a really large team. It's like a marathon effort with some sprints in the middle. The team is working very hard, but they can see the finish line. I guarantee that it will deliver a huge improvement in performance and power consumption over the previous generation. ”
— Suzanne Plummer, Zen team leader, on September 19th, 2015.[18]

Reportedly, the Zen architecture will be built on a more efficient 14 nanometer process (probably GloFo 14 LPP), rather than the 32 nm and 28 nm processes of previous AMD FX CPUs and AMD APUs, respectively.[19] The "Summit Ridge" Zen family will also feature a unified AM4 socket with its GPU-equipped "Bristol Ridge" APU counterparts,[20] and feature DDR4 support and a 95 W TDP.[19] Zen does not support DDR3; only 7th generation AMD APUs (also fitting the AMD AM4 unified socket) support DDR3 and DDR4. While newer roadmaps don't confirm the TDP for desktop products, they suggest a range for low-power mobile products with up to two Zen cores from 5 to 15 W and 15 to 35 W for performance-oriented mobile products with up to four Zen cores.[21]

Zen will support the hardware random number generator, RDSEED.[22]

Each Zen core will have four integer units, two address generation units and four floating point units, and the decoder can decode four instructions per clock cycle. L1 cache size is 32 KiB and L2 cache size 512 KiB per core. Two of the floating point units are adders, two are multipliers.[23]

Development

AMD began planning the Zen microarchitecture shortly after re-hiring Jim Keller in early 2012.[24]

The team in charge of the Zen microarchitecture was led by Keller until he left in September 2015 after a 3-year tenure.[25]

Zen was originally planned for 2017 following the ARM64-based K12 sister core, but on AMD's 2015 Financial Analyst Day it was revealed that K12 was delayed in favour of the Zen design, to allow it to enter the market within the 2016 timeframe,[8] with the release of first Zen-based processors expected for October 2016.[11]

In November 2015 a source inside AMD reported that Zen microprocessors had been tested and "met all expectations" with "no significant bottlenecks found".[1][26]

In December 2015, it was rumored that Samsung may be contracted as a fabricator for AMD's 14 nm FinFET processors, including both Zen and their upcoming Polaris GPU architecture.[27]

In January 2016, Global foundries[28] announced the production of Polaris GPU for AMD on its (FinFET) 14nm Low Power Plus.

Advantages over predecessors

Zen's from-scratch design is notably different from its predecessors, with many different types of changes and enhancements being made across the board in hopes of making Zen more competitive with Intel's architectures, and the software most often built with Intel's processor features in mind.[29] Processors built using Zen will utilize low-power 14 nm FinFET silicon. Prior to Zen, AMD's smallest process size was 28 nm, as utilized by their Kaveri APUs.[30][31]

Performance

One of Zen's major goals was to focus on performance per-core, and it is rumored to have 40% higher instructions per clock over its predecessor, Excavator, which in comparison offered 4-15% improvement over previous architecture.[32] Zen will also support simultaneous multithreading, a feature previously offered in some Intel processors in the form of HyperThreading.[33] Previous Bulldozer-derived chips from AMD had single blocks of resources that had to be shared between cores, resulting in lower performance per core in multi-threaded applications.[34]

Memory

APUs utilizing the Zen architecture will also support High Bandwidth Memory (HBM).[35] Previous APUs from AMD had to rely on traditional shared DDR3 RAM for video memory.

Zen supports DDR4 memory (up to 8 channels).[36] Previous CPUs and APUs from AMD only supported up to DDR3.

Power consumption

All processors using the Zen architecture will be built at the 14 nm node on FinFET silicon, potentially reducing power consumption and heat over their 28 nm and 32 nm non-FinFET predecessors.

Heat output

Also a byproduct of lower power usage and leakage, processors built on the 14 nm node with the Zen architecture are expected to produce less heat than their predecessors.

Socket compatibility

Due to Zen integrating previously external motherboard components in an SoC-like nature, Zen's AM4 socket will unify the future variants of older AM1, FM2+, and AM3+ sockets.

Cooling

Although the cooling solution is not a component of the architecture itself, AMD announced that their quieter and more powerful CPU cooler, named "Wraith", would be included with Zen chips.[37]

Products

Official names for products utilizing the Zen architecture have not yet been officially released, as of January 2016. Zen is expected to be utilized in future FX CPUs, future Opteron CPUs, and future APUs.[35][38]

Zen will also be utilized for future Opteron server processors.[5][39]

See also

References

  1. 1 2 "GlobalFoundries announces 14nm validation with AMD Zen silicon". ExtremeTech.
  2. ↑ Jarred Walton. "AMD’s Polaris Shoots for the Stars". pcgamer.
  3. ↑ "Details of AMD Zen 16-core x86 APU emerge".
  4. ↑ "AMD Zen-based 8-core Desktop CPU Arrives in 2016, on Socket FM3". TechPowerUp.
  5. 1 2 Fuad Abazovic. "The next generation Opteron has 32 Zen x86 cores".
  6. ↑ "CERN Engineer Leaks AMD Zen Details, Claims Up To 32 Cores - HotHardware". 11 February 2016.
  7. ↑ Moammer, Khalid (September 9, 2014). "AMD's Next Gen x86 High Performance Core is Zen". WCCF Tech. Retrieved January 15, 2015.
  8. 1 2 Ryan Smith (6 May 2015). "AMD’s 2016-2017 x86 Roadmap: Zen Is In, Skybridge Is Out". AnandTech.
  9. ↑ Bo Moore. "AMD's next-gen Zen CPU due in 2016". pcgamer.
  10. ↑ "AMD hints at high-performance Zen x86 architecture". bit-tech. 11 September 2014. Retrieved 15 December 2014.
  11. 1 2 "AMD set to release first ‘Zen’-based microprocessors in late 2016 – document". KitGuru.net. 12 June 2015. Retrieved 30 August 2015.
  12. ↑ Brad Chacos (8 January 2016). "AMD Zen-based CPUs and APUs will unify around Socket AM4". PCWorld.
  13. ↑ "AMD Zen-based CPUs and APUs Will Have Unified Socket AM4 - Legit Reviews". Legit Reviews.
  14. ↑ "Weekend tech reading: AMD 'Zen' and their return to high-end CPUs, tracking Windows pirates - TechSpot". techspot.com. Retrieved 2015-05-12.
  15. ↑ "AMD: Zen chips headed to desktops, servers in 2016 - The Tech Report - Page 1". techreport.com. Retrieved 2015-05-12.
  16. 1 2 Anton Shilov (11 September 2014). "AMD: ‘Bulldozer’ was not a game-changer, but next-gen ‘Zen’ will be". KitGuru. Retrieved 1 February 2015.
  17. ↑ Lilly, Paulk (11 February 2016). "CERN Engineer Leaks AMD Zen Details Confirming 32 Core Implementation And SMT". hothardware.com.
  18. ↑ Kirk Ladendorf - For the American-Statesman. "Amid challenges, chipmaker AMD sees a way forward".
  19. 1 2 "14nm AMD Zen CPU Will Have DDR4 and Simultaneous Multithreading". Softpedia. 28 January 2015. Retrieved 31 January 2015.
  20. ↑ "AMD Reveals Single Socket For Zen CPU, APU". tomshardware.com. Retrieved 8 January 2016.
  21. ↑ "AMD's next gen CPU Zen". Shattered.Media. May 2015.
  22. ↑ "AMD Starts Linux Enablement On Next-Gen "Zen" Architecture". Phoronix. 17 March 2015. Retrieved 17 March 2015.
  23. ↑ "AMD's Zen core (family 17h) to have ten pipelines per core".
  24. ↑ Jim Keller On AMD's Next-Gen High Performance x86 Zen Core & K12 ARM Core. YouTube. 7 May 2014.
  25. ↑ "Jim Keller Leaves AMD". Anand tech. Retrieved 2015-10-14.
  26. ↑ "OC3D :: Article :: AMD Tests Zen CPUs, "Met All Expectation" with no "Significant Bottlenecks" found :: AMD Tests Zen CPUs, Met All Expectation with no Significant Bottlenecks found".
  27. ↑ "Samsung to fab AMD Zen & Arctic islands on its 14 nm Finfet node", Tech power up.
  28. ↑ "Global foundries to build new 14 nm GPUs for AMD", Foundry files (World wide web log), Global foundries, 2016-01-07.
  29. ↑ "AMD’s next-gen CPU leak: 14nm, simultaneous multithreading, and DDR4 support". ExtremeTech.
  30. ↑ "AMD: We have taped out our first FinFET products". KitGuru.
  31. ↑ "CES: AMD finally unveils 28nm APU Kaveri to battle Intel Haswell". http://www.theinquirer.net. External link in |work= (help)
  32. ↑ Ian Cutress. "IPC Increases: Double L1 Data Cache, Better Branch Prediction - AMD Launches Carrizo: The Laptop Leap of Efficiency and Architecture Updates".
  33. ↑ "AMD Zen Confirmed for 2016, Features 40% IPC Improvement Over Excavator".
  34. ↑ Horia Despa (5 October 2015). "AMD Zen Will Feature Double Data Crunching IPC and Floating Point Units per Core". softpedia.
  35. 1 2 "Zen-based APU with HBM to be AMD Carrizo successor".
  36. ↑ "AMD's Zen processors to feature up to 32 cores, 8-channel DDR4". TechSpot.
  37. ↑ "CES 2016: AMD Announces Wraith Cooler".
  38. ↑ "AMD Zen FX CPUs, APUs Release Details Surface, Top-Notch Performance In The Cards". Tech Times.
  39. ↑ "32-core AMD Opteron to feature quad-die MCM design". KitGuru.
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