AMD Sued Over Allegedly Misleading Bulldozer Core Count

An anonymous reader writes: A class action suit accuses AMD of misleading buyers about the number of cores in its Bulldozer-based CPUs. The complaint claims that the chips effectively had only four cores, while AMD claims there are eight. According to Ars: "AMD's multi-core Bulldozer chips use a unique design that combines the functions of what would normally be two discrete cores into a single package, which the company calls a module. Each module is identified as two separate cores in Windows, but the cores share a single floating point unit and instruction and execution resources. This is different from Intel's cores, which feature independent FPUs. The suit claims that Bulldozer's design means its cores cannot work independently, and as a result, cannot perform eight instructions simultaneously and independently. This, the claim continues, results in performance degradation, and average consumers in the market for a CPU lack the technical expertise to understand the design of AMD's processors and trust the company to give accurate specifications regarding its CPUs."

Comments

Extremetech sums it up pretty easily... :

[Anonymous Coward]

http://www.extremetech.com/extreme/217672-analysis-amd-lawsuit-over-false-bulldozer-chip-marketing-is-without-merit

Re:So AMD called their Hyperthreading a CPU core?

[Entrope]

AMD's CPU architecture has a similar purpose as hyperthreading -- to share hardware resources between what looks to the OS like independent cores -- but the tradeoff is different. Intel's hyperthreading approach only works to cover memory latency, because the hyperthreads share so many physical resources (I think basically everything except register files and hyperthreading-related state). AMD's is somewhat different in that each "module" has two independent integer ALUs, register files, and L1 data caches. The module has one L1 instruction cache, one L2 data cache, one FPU, and one instruction fetch/decode unit.

But AMD has always been pretty up-front about this architecture. There is maybe a cause of action against resellers who package the AMD chips into systems and do gloss over which aspects each "core" shares with another core, but AMD publicly presented the core-vs-module distinction well before the chips were released.

Pretty Laughable

[TooManyNames]

Why is this even reported? This suit isn't going to go anywhere (unless AMD's lawyers are extremely incompetent, and the judge is extremely incapable of understanding basics about computer architecture and ISAs).

The AMD cores shared an FPU, sure, but sharing a resource doesn't mean that cores cannot execute simultaneously. The AMD cores still have independent integer-based execution units (instruction registers, register files, ALUs, branch counters, etc.), after all, and are fully capable of executing integer instructions simultaneously (which accounts for the vast majority of instructions under typical loading).