Reply to post: what kind of apps were impacted?

Core blimey... When is an AMD CPU core not a CPU core? It's now up to a jury of 12 to decide

Nate Amsden

what kind of apps were impacted?

From the previous article https://www.theregister.co.uk/2015/11/06/amd_sued_cores/

"it claims it is impossible for an eight-core Bulldozer-powered processor to truly execute eight instructions simultaneously – it cannot run eight complex math calculations at any one moment due to the shared FPU design"

This article seems to be referring to desktop processors though I assume the Opterons at the time were affected as well ? (I have several Opteron 6176 and 6276s in service still as vmware hosts - though checking now at least Wikipedia says only the 4200/6200 Opterons were bulldozer).

So if desktop processors were affected I am curious what sorts of apps would be impacted seriously by this? I mean I expect in most games and 3D rendering type apps that GPUs are far more important than FPU for math calculations. Perhaps media encoding ? I think that is often accelerated by the MMX/SSE type instructions.

I would assume that CPU(FPU) based math would be more common in the HPC space (even with GPUs), and I can certainly see a case for an issue there - however at the same time I would expect any HPC customer to do basic testing of the hardware to determine if the performance is up to their expectations regardless of what the claims might be. Testing math calculation performance should be pretty simple.

I want to say I was aware of this FPU issue years ago when I was buying the Opterons, and then, and even now I don't care about the fewer FPUs, I wanted more integer cores(for running 50-70+ VMs on a server). I really have had no workloads that(as far as I am aware at least) are FPU intensive. Though it certainly would be nice if it was possible to measure specifically FPU utilization on a processor, much like I wish it was easy to measure PCI bus bandwidth utilization( not that I have anything that seriously taxes the PCI bus(again that I am aware of) but having that data would be nice.

I think back to when Intel launched their first quad core processor, or one of the first, I think it was around 2006-2007. They basically took two dual core procesors and "glued" them together to make a quad core. I remember because AMD talked shit about Intel's approach as AMD had a "true" quad core processor.. fast forward a decade and it seems everyone is gluing modules together.

POST COMMENT House rules

Not a member of The Register? Create a new account here.

  • Enter your comment

  • Add an icon

Anonymous cowards cannot choose their icon