What is a core?

[lakedude]

Yes, but what is a rendering pipeline?

My ROPs are bigger than your ROPs!

 

[Eeqmcsq]

My definition of a "core" is the logical entity that can execute a second thread so that if you run 2 threads or processes that are performing an identical task (such as sorting an identically shuffled array of ints or floats), then both tasks will complete in about the same amount of time as doing 1 task, ignoring turbo boost and background OS processes.

For the Bulldozer series, that second integer unit adds about 60-80% more parallel performance. That's not a full 2nd core, but that's also a significant chunk of added parallel performance that can't simply be treated like a bit of "bonus" performance, like hyperthreading.

So I convert the Bulldozer "shared cores" count into units of "discrete cores". For example, if a 2nd Bulldozer "core" adds 60-80% more parallel performance, then an 8 "shared-core" CPU will perform like a 6.4 - 7.2 "discrete-core" CPU. If Steamroller's tweaks increase this by another 10%, then a 2nd Steamroller core" adds 70-90% parallel performance, and an 8 "shared-core" CPU will perform like 6.8 - 7.6 "discrete-core" CPU.

 

[cantholdanymore]

Is there an academic definition?

 

[NostaSeronx]

Is there an academic definition

IBM defines a core as:

Core - A functional unit within a computing device that interprets and executes software instructions.

This is a bit vague.
For the core to interpret and execute software instructions it needs:
-A Control Unit
-A Datapath
-A Instruction Bus
-A Data Bus

 

[Idontcare]

Is there an academic definition?

Yes, but as you might expect the definition is basically one developed for the purpose of legal rigour.

There is a reason the term came to be used in the world of x86 processors, it wasn't invented by (or for) the CPU industry.

All integrated circuits contain a "core". Both in the physical (layout) sense as well as in the logic (conceptual) sense. Your ethernet chip has a core, your GPU has a core, your CPU has a core, even your DRAM chips have a core - sometimes they have more than one, but no IC has zero cores.

 

[Ben90]

L3 can be shared between cores, and thats all. The best example of a core is the Q6600, that was a true desktop quad core, none of this AMD half core quadroupled into two cores bullshit, and intel HT further muddies the water.

By your own definition, the Q6600 was a single core processor.

 

[cantholdanymore]

Yes, but as you might expect the definition is basically one developed for the purpose of legal rigour.

There is a reason the term came to be used in the world of x86 processors, it wasn't invented by (or for) the CPU industry.

All integrated circuits contain a "core". Both in the physical (layout) sense as well as in the logic (conceptual) sense. Your ethernet chip has a core, your GPU has a core, your CPU has a core, even your DRAM chips have a core - sometimes they have more than one, but no IC has zero cores.

Thanks,

 

[Schmide]

L3 can be shared between cores, and thats all. The best example of a core is the Q6600, that was a true desktop quad core, none of this AMD half core quadroupled into two cores bullshit, and intel HT further muddies the water.

Humanaaa what? The q6600 was 2 dual core modules slapped together over the FSB!

 

[lakedude]

Humanaaa what? The q6600 was 2 dual core modules slapped together over the FSB!

^Yep, 2 dual cores duct taped together. AMD eventually came out with a "true quad core" design but the sad thing was the 6600 was still faster, duct tape and all...