Bulldozer (microarchitecture)
AMD claims dramatic performance-per-watt efficiency improvements in high-performance computing (HPC) applications with Bulldozer cores.
According to AMD, Bulldozer-based CPUs are based on GlobalFoundries' 32 nm Silicon on insulator (SOI) process technology and reuses the approach of DEC for multitasking computer performance with the arguments that it, according to press notes, "balances dedicated and shared computer resources to provide a highly compact, high units count design that is easily replicated on a chip for performance scaling.
"[6] In other words, by eliminating some of the "redundant" elements that naturally creep into multicore designs, AMD has hoped to take better advantage of its hardware capabilities, while using less power.
[10][11] In a retrospective review, Jeremy Laird of APC magazine commented on Bulldozer issues, noted that it was slower than outgoing Phenom II K10 design, and that the PC software ecosystem had not yet "embraced" the multi-threaded model.
Prior examples of such an approach to unconventional multithreading can be traced way back to the 2005 Sun Microsystems' UltraSPARC T1 CPU.
In terms of hardware complexity and functionality, a Bulldozer CMT module is equal to a dual-core processor in its integer calculation capabilities, and to either a single-core processor or a handicapped dual-core in terms of floating-point computational power, depending on whether the code is saturated in floating point instructions in both threads running on the same CMT module, and whether the FPU is performing 128-bit or 256-bit floating point operations.
(Both of these last two comparisons make the assumption that the processor possesses an equally wide and capable execution core, integer-wise and floating-point-wise, respectively.)
Both CMT and SMT are at peak effectiveness while running integer and floating point code on a pair of threads.
The disadvantage for CMT is a greater number of idle integer execution units in a single threaded case.
The longer pipeline allowed the Bulldozer family of processors to achieve a much higher clock frequency compared to its K10 predecessors.
However, due to K10's somewhat wider core (in addition to the lack of refinements and optimizations in a first generation design) the Bulldozer architecture typically performed with somewhat lower IPC compared to its K10 predecessors.
It was not until the refinements made in Piledriver and Steamroller, that the IPC of the Bulldozer family distinctly began to exceed that of K10 processors such as Phenom II.
[35][36] In November 2015, AMD was sued under the California Consumers Legal Remedies Act and Unfair Competition Law for allegedly misrepresenting the specifications of Bulldozer chips.
It was discovered that the FX-8150 performed poorly in benchmarks that were not highly threaded, falling behind the second-generation Intel Core i* series processors and being matched or even outperformed by AMD's own Phenom II X6 at lower clock speeds.
AMD stated that they had provided a BIOS update to several motherboard manufacturers (namely: Asus, Gigabyte Technology, MSI, and ASRock) that would fix the problem.
