Excavator (microarchitecture)

AMD Excavator Family 15h is a microarchitecture developed by AMD to succeed Steamroller Family 15h for use in AMD APU processors. On October 12, 2011, AMD revealed Excavator to be the code name for the fourth-generation Bulldozer-derived core.

The Excavator-based APU for mainstream applications is called Carrizo and was released in 2015.^[2][3] The Carrizo APU is designed to be HSA 1.0 compliant.^[4] An Excavator-based APU and CPU variant named Toronto for server and enterprise markets will also be available.^[5]

Excavator has been confirmed to be AMD's final revision of the 'Bulldozer' family, with two new microarchitectures replacing Excavator a year later.^[6][7] The next generation sister architectures will be the x86-64 Zen and AArch64 K12 architectures.^[8][9]

Architecture

Excavator is expected to support new instructions such as AVX2, BMI2 and RdRand.^[10] Excavator is also expected to come with DDR3 and DDR4 memory controllers, currently not known if on the same die or mutually exclusive.^[1] Excavator is designed using High Density (aka "Thin") Libraries normally used for GPUs to reduce electric energy consumption and die size, delivering a 30 percent increase in efficient energy use.^[11] Excavator can process up to 15% more instructions per clock compared to AMD's previous core Steamroller.^[12]

Processors

APU lines

There are three APU lines announced or released:

1. Budget and mainstream markets (mobile only): Carrizo APU
   • The Carrizo mobile APUs were launched in 2015 based on Excavator x86 cores and featuring Heterogeneous System Architecture for integrated task sharing between CPUs and GPUs, which allows a GPU to perform compute functions, which is claimed provide greater performance increases than shrinking the feature size alone.^[4]
2. Budget and mainstream markets (desktop and mobile): Bristol Ridge and "Stoney Ridge" APU^[13]
   • Bristol Ridge APUs will utilize socket AM4 and DDR4 RAM
   • Bristol Ridge APUs have up to 4 Excavator CPU cores and up to 8 3rd generation GCN GPU cores
   • Up to a 20% CPU performance increase over Carrizo
   • TDP of 15W to 65W, 15–35W for mobile
3. Enterprise and server markets: Toronto APU
   • The Toronto APU for server and enterprise markets will feature four x86 Excavator CPU core modules and Volcanic Islands integrated GPU core. The available Toronto APU specifications provides more detail on the upcoming Carrizo APU.^[5]
   • The Excavator four modular cores has a greater advantage with IPC than Steamroller. The improvement is 4–15%.
   • Support for HSA/hUMA, DDR3/DDR4, PCIe 3.0, GCN 1.2^[4][5][9]
   • The Toronto APU will be available in BGA and SoC variants. The SoC variant will have the southbridge on the same die as the APU to save space and power and to optimize workloads.
   • A complete system with a Toronto APU would have a maximum power usage of 70 W.^[5]

CPU Desktop lines

There are no plans for Steamroller (3rd gen Bulldozer) or Excavator (4th gen Bulldozer) architectures on high-end desktop platforms.

Excavator CPU for Desktop announced on 2nd Feb 2016, named Athlon X4 845.^[14]

Server lines

The AMD Opteron roadmaps for 2015 show the Excavator-based Toronto APU and Toronto CPU intended for 1 Processor (1P) cluster applications:^[5]

• For 1P Web and Enterprise Services Clusters:
  • Toronto CPU – quad-core x86 Excavator architecture
  • plans for Cambridge CPU – 64-bit AArch64 core
• For 1P Compute and Media Clusters:
  • Toronto APU – quad-core x86 Excavator architecture
• For 2P/4P Servers:
  • Warsaw CPU – 12/16 core x86 Piledriver (2nd gen Bulldozer) (Opteron 6338P and 6370P)
  • no plans for Steamroller (3rd gen Bulldozer) or Excavator (4th gen Bulldozer) architectures on high-end multi-processor platforms

References