Steamroller (microarchitecture)

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Produced beginning of 2014
Common manufacturer(s)
Min. feature size 28 nm SHP[1]
Instruction set AMD64
Predecessor Piledriver
Successor Excavator
Core name(s)

Steamroller is a microarchitecture developed by AMD, which succeeded Piledriver in the beginning of 2014.[3] Steamroller APUs continue to use two-core modules as their predecessors, while aiming at achieving greater levels of parallelism.


Steamroller still features two-core modules found in Bulldozer and Piledriver designs called clustered multi-thread (CMT), meaning that one module is equal to a dual-core processor.[4] The focus of Steamroller is for greater parallelism.[5] Improvements will center on independent instruction decoders for each core within a module, 25% more of the maximum width dispatches per thread, better instruction schedulers, improved perceptron branch predictor, larger and smarter caches, up to 30% less instruction cache misses, branch misprediction rate reduced by 20%, dynamically resizable L2 cache, micro-operations queue,[6] more internal register resources and improved memory controller.

AMD estimated that these improvements will increase instructions per cycle (IPC) up to 30% compared to the first-generation Bulldozer core while maintaining Piledriver's high clock rates with decreased power consumption.[4] The final result was a 9% single-threaded IPC improvement, and 18% multi-threaded IPC improvement over Piledriver.[7]

Steamroller, the microarchitecture for CPUs, as well as Graphics Core Next, the microarchitecture for GPUs, are paired together in certain product lines, and both support certain features specified in Heterogeneous System Architecture in hardware.


In 2011, AMD announced a third-generation Bulldozer-based line of processors for 2013,[8] with Next Generation Bulldozer as the working title, using the 28 nm manufacturing process.[9]

On 21 September 2011, leaked AMD slides indicated that this third generation of Bulldozer core was codenamed Steamroller.[10][11]

In January 2014, Kaveri APUs became available.[12]


APU lines[edit]

There are two main APU lines announced:

  1. Kaveri A-series APU
  2. Berlin APU
    • Enterprise and server markets: The Berlin APU will be similar to Kaveri, featuring four Steamroller cores, up to 512 stream processors, and support for ECC memory.[25]

Feature overview for APU branded product lines[edit]

The entire AMD Accelerated Processing Unit lines and some of their features
Brand Brazos
(low power)
Llano Trinity & Richland Kabini & Temash
(low power)
Kaveri Beema & Mullins
(low power)
Carizzo Unknown
(low power)
Released Jan 2011 Aug 2011 Oct 2012 May 2013 Jan 2014 Q2 2014 2015 2015
Fab (nm) TSMC 40 nm GlobalFoundries 32 nm SOI 28 28 28 TBA TBA
Socket Socket FT1 Socket FM1
Socket FS1
Socket FM2
Socket FS1r2
Socket FP2
Socket AM1
Socket FT3
Socket FM2+
Socket FP3
Socket AM1
Socket FT3b
CPU cores Bobcat K10 Piledriver Jaguar Steamroller Puma Excavator TBA
3D engine block "Cedar" (VLIW5) "Northern Islands" (VLIW4) "Sea Islands" TBA TBA
FYI TeraScale Graphics Core Next (Mantle, HSA)
Unified shader model
Unified Video Decoder UVD 3 UVD 4 UVD 4.2 TBA TBA
Video Codec Engine N/A VCE 1.0 VCE 2.0 TBA TBA
TrueAudio N/A Yes[26] N/A[27] TBA TBA
Max. № of displays1 2 2–3 2–4 2 2–4 2–_ TBA TBA
Linux DRM/KMS driver[28][29] Yes WiP N/A N/A
Mesa 3D driver[29] Yes WiP N/A N/A
AMD Catalyst Yes N/A N/A
  • 1 maximum of two non-DisplayPort monitors, and a maximum of second number of DisplayPort monitors, but maximum of six!

FX lines[edit]

In November 2013, AMD confirmed it will not update the FX series in 2014, neither its current Socket AM3+ version, nor will it receive a Steamroller version with a new socket.[30][31] An unconfirmed article, citing anonymous sources with knowledge of AMD's internal roadmap extending into 2015, also did not mention plans for a new FX processor.[32]

Server lines[edit]

AMD's server roadmaps for 2014 are showing only the above described quad-core Steamroller Berlin APU, and a Piledriver-based Warsaw CPU having up to 16 cores.[33]


  1. ^ "Page 2 - AMD Kaveri A10-7850K and A8-7600 review: Was it worth the wait for the first true heterogeneous chip?". ExtremeTech. Retrieved 2014-02-19. 
  2. ^ "AMD Vows Not to Drop Microprocessor Sockets in Next Two Years". X-bit labs. 2012-12-05. Retrieved 2013-09-29. 
  3. ^ "AMD Kaveri Review: A8-7600 and A10-7850K Tested". 2014-01-14. Retrieved 2014-02-08. 
  4. ^ a b "AMD: We Are On Track With Steamroller Micro-Architecture in 2013". X-bit labs. 2013-03-31. Retrieved 2013-09-29. 
  5. ^ Su, Lisa (2012-02-02). "Consumerization, Cloud, Convergence." (PDF). AMD 2012 Financial Analyst Day. Sunnyvale, California: Advanced Micro Devices. p. 26. Retrieved 2012-02-04. 
  6. ^ Anand Lal Shimpi (2012-08-28). "AMD's Steamroller Detailed: 3rd Generation Bulldozer Core". Retrieved 2013-11-16. 
  7. ^ Miller, Michael J. (2014-02-14). "Ivytown, Steamroller, 14 and 16nm Process Highlight ISSCC". Retrieved 2014-02-19. 
  8. ^ Anton Shilov (2010-11-09). "AMD Plans to Release Twenty-Core Microprocessor in 2012". X-bit labs. Retrieved 2012-01-23. 
  9. ^ "2012 Financial Analyst Day". 2012-02-02. Retrieved 2013-09-29. 
  10. ^ "Hosszútávú mobil útiterv szivárgott ki az AMD-től - PROHARDVER! Processzor hír". 2011-09-21. Retrieved 2012-01-23. 
  11. ^ "Nuove roadmap AMD sulle future APU in programma nel 2012 e nel 2013 per il mercato mobile". 2011-09-21. Retrieved 2012-01-23. 
  12. ^ Joel Hruska (2014-01-14). "AMD Kaveri A10-7850K and A8-7600 review: Was it worth the wait for the first true heterogeneous chip?". Retrieved 2014-01-17. 
  13. ^ "AMD Unleashes More Details About Kaveri: HSA, TrueAudio, Mantle". 
  14. ^ "AMD Unveils Innovative New APUs and SoCs that Give Consumers a More Exciting and Immersive Experience". Retrieved 2013-09-29. 
  15. ^ Joel Hruska (2013-11-11). "AMD Confirms Kaveri Integrated Graphics Has 512 GPU Cores, Runs Battle Field 4 at APU13". Retrieved 2013-12-27. 
  16. ^ "AMD’s Next-Gen "Kaveri" APUs Will Require New Mainboards". X-bit labs. 2013-05-30. Retrieved 2013-09-29. 
  17. ^ "A technical look at AMD’s Kaveri architecture". SemiAccurate. 2014-01-15. 
  18. ^ "Multi-monitor: Civilization V on A10-7850K "Kaveri"". 
  19. ^ "AMD A8-7600 Kaveri APU review - The Embedded GPU - HSA & hUMA". 2014-01-14. 
  20. ^ "AMD’s Next-Gen "Kaveri" APUs Will Require New Mainboards.". 2013-05-30. Retrieved 06-09-2013. 
  21. ^ "AMD Kaveri APU Architecture Detailed". 
  22. ^ "AMD to add ARM processors to boost chip security". June 14, 2012. Retrieved September 3, 2013. 
  23. ^ "AMD and ARM Fusion redefine beyond x86". Retrieved 2013-11-10. 
  24. ^ "AMD A10-7850K Graphics Performance". Retrieved April 2, 2014. 
  25. ^ "AMD Berlin Server APU Provides Glimpse At Upcoming Kaveri APU With 4 Steamroller Cores and 512 GCN SPs". 2013-06-19. Retrieved 2013-09-29. 
  26. ^ "A technical look at AMD’s Kaveri architecture". Semi Accurate. Retrieved 6 July 2014. 
  27. ^ "Mullins and Beema do not support HSA nor TrueAudio". 
  28. ^ Airlie, David (2009-11-26). "DisplayPort supported by KMS driver mainlined into Linux kernel 2.6.33". Retrieved 2014-07-02. 
  29. ^ a b "Radeon feature matrix". 
  30. ^ Anton Shilov (2013-11-13). "AMD Cans Plans to Introduce Next-Gen FX Microprocessors Next Year". 
  31. ^ Josh Walrath (2013-09-04). "AMD's Processor Shift: The Future Really is Fusion". Retrieved 2013-09-29. 
  32. ^ "AMD updates product roadmap for 2014 and 2015". 2013-08-26. Retrieved 2013-09-29. 
  33. ^ "Berlin, Warsaw are the future of AMD's x86 server lineup". The Tech Report. 2013-06-18. Retrieved 2013-09-29.