AMD Steamroller Family 15h is a microarchitecture developed by AMD,
which succeeded Piledriver in the beginning of 2014 as the
third-generation Bulldozer-based microarchitecture. Steamroller APUs
continue to use two-core modules as their predecessors, while aiming at
achieving greater levels of parallelism. Microarchitecture
Steamroller still features two-core modules found in Bulldozer and
Piledriver designs called clustered multi-thread, meaning that one module is
equal to a dual-core processor. The focus of Steamroller is for greater
parallelism. Improvements 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% fewer instruction cache misses, branch
misprediction rate reduced by 20%, dynamically resizable L2 cache,
micro-operations queue, more internal register resources and improved memory
controller. AMD estimated that these improvements
will increase instructions per cycle up to 30% compared to the first-generation
Bulldozer core while maintaining Piledriver's high clock rates with
decreased power consumption. The final result was a 9% single-threaded IPC
improvement, and 18% multi-threaded IPC improvement over Piledriver.
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. History
In 2011, AMD announced a third-generation Bulldozer-based line of
processors for 2013, with Next Generation Bulldozer as the working
title, using the 28 nm manufacturing process.
On 21 September 2011, leaked AMD slides indicated that this third generation of
Bulldozer core was codenamed Steamroller.
In January 2014, Kaveri APUs became available.
Processors = APU lines=
There are two main APU lines announced: Kaveri A-series APU
Desktop budget and mainstream markets: The Trinity / Richland APU line is
scheduled to be replaced on 14 January 2014 by the Kaveri APU line, as the
third generation of A10, A8, A6 and A4 series for the desktop market. Currently
known new model is a quad-core A10-7850K APU, with a 3.7 GHz core frequency and 4
MB L2 cache, incorporating a 720 MHz GPU with 512 stream processors and 856
GFLOPS of total processing power. These APUs have two to four enhanced
Steamroller B cores, a GCN 1.1 Volcanic Islands integrated GPU, and two
integrated DDR3 memory controllers. Kaveri APUs utilize the new FM2+ socket,
thus they are not backwards compatible with the previous generation of FM2
motherboards. SIP blocks: Unified Video Decoder, Video
Coding Engine, TrueAudio AMD Eyefinity up to 4 monitors, 4K Ultra
HD support, DisplayPort 1.2 Support Socket FM2+-only, Socket FM2 is not
supported, support for PCIe 3.0 Two or four CPU cores based on the
Steamroller microarchitecture Three to eight Compute Units based on
the revised Graphics Core Next microarchitecture; 1 Compute Unit
consists of 64 Unified Shader Processors : 4 Texture Mapping Units : 1 Render
Output Unit AMD Heterogeneous System Architecture
2.0 Dual-channel DDR3 memory controller
Integrated custom ARM Cortex-A5 co-processor with TrustZone Security
Extensions Select models support AMD Hybrid
Graphics by using a Radeon R7 240 or R7 250 discrete graphics card.
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.
= FX lines= 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. 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. = Server lines=
AMD's server roadmaps for 2014 show: Berlin APU - quad-core x86 Steamroller
architecture for 1 Processor compute and media clusters
focused on cloud and media streaming Berlin CPU - quad-core x86 Steamroller
architecture for 1P web and enterprise services clusters
focused on big data processing and HPC Seattle CPU - 4/8 core AArch64
Cortex-A57 architecture for 1P web and enterprise services clusters low-end
applications with power-saving options Warsaw CPU - up to 16 core x86
Piledriver architecture for 2P/4P servers no plans for Steamroller or
Excavator architectures on high-end multi-processor platforms
References