SoylentNews is people
SoylentNews
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: 2) by shortscreen on Thursday January 24 2019, @10:51AM (1 child)
This could get very foggy. It's normal for some instructions to take multiple cycles. These are super scalar CPUs, which means it's also normal for multiple instructions to execute in one cycle (on one core). With the pipelined design, it's also possible for multiple instructions to be "executing" during a cycle even if none of them happen to finish on that cycle.
I think it's reasonable to say that AMD's chip had eight cores, with pairs of cores having contention for shared FPU resources. Just like any multi-core chip has shared I/O and memory bandwidth. But chips with hyperthreading don't count the additional thread as a separate core, so another way to look at it would be to compare the functionality that is duplicated on one core with HT versus the two cores in AMD's module. (Since I don't know anything about HT I can't currently answer that)
(Score: 2) by FatPhil on Friday January 25 2019, @08:22AM
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves