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Core blimey... When is an AMD CPU core not a CPU core? It's now up to a jury of 12 to decide
A class-action lawsuit against AMD claiming false advertising over its "eight core" FX processors has been given the go-ahead by a California judge.
US district judge Haywood Gilliam last week rejected [PDF] AMD's claim that "a significant majority" of people understood the term "core" the same way it did as "not persuasive."
What tech buyers imagine represents a core when it comes to processors would be a significant part of such a lawsuit, the judge noted, and so AMD's arguments were "premature."
The so-called "eight core" chips contain four Bulldozer modules, the lawsuit notes, and these "sub-processors" each contain a pair of instruction-executing CPU cores. So, four modules times two CPU cores equals, in AMD's mind, eight CPU cores.
And here's the sticking point: these two CPU cores, within a single Bulldozer module, share caches, frontend circuitry, and a single floating point unit (FPU). These shared resources cause bottlenecks that can slow the processor, it is claimed.
The plaintiffs, who sued back in 2015, argue that they bought a chip they thought would have eight independent processor cores – the advertising said it was the "first native 8-core desktop processor" – and paid a premium for that.
(Score: 3, Informative) by sjames on Wednesday January 23 2019, @11:41PM
TL/DR: It's complicated.
In a full core, you have the instruction decoder/dispatcher assigning work to a full set of integer and floating point execution units. In hyperthreading, you have two decoders dispatching different threads of execution to a single set of integer and floating point units.
On that AMD processor, you have 2 dispatchers dispatching to 2 sets of integer units but just one set of floating point units. It is really half way between the two extremes.
How useful that is depends on the workload.