For those of you using a Threadripper build, or any recent AMD CPU, you may have concerns with the Infinity Fabric induced latency between CCXs, and further latency between dies. I dug through multiple posts to try and find exactly what cores were associated with what CCX/die, and after finding insufficient info, decided to ask AMD and my motherboard supplier, Gigabyte.
For those of you who had not seen the informative post on AMD's latency tests, it has been found that base Ryzen uses sequential numberings (no interleave) for their core assignments. Lodging a ticket with AMD support confirms this for Threadripper as well. Gigabyte also returned the same info for physical cores, but gave no info on logical ones.
Ultimately that means cores 0-1 are both logically related, cores 0-7 are on the same CCX, and (if on Threadripper) cores 0-15 are on the same die.
This will hopefully help someone else come across the information more quickly and reduce their struggle by some small amount. I hate to cop out, but I'm at work now, so if anyone has an article they feel will supplement this info, please comment it below.
Ryzen/Threadripper PSA: Core Numberings and Assignments
in VM Engine (KVM)
Posted
Hi everyone,
For those of you using a Threadripper build, or any recent AMD CPU, you may have concerns with the Infinity Fabric induced latency between CCXs, and further latency between dies. I dug through multiple posts to try and find exactly what cores were associated with what CCX/die, and after finding insufficient info, decided to ask AMD and my motherboard supplier, Gigabyte.
For those of you who had not seen the informative post on AMD's latency tests, it has been found that base Ryzen uses sequential numberings (no interleave) for their core assignments. Lodging a ticket with AMD support confirms this for Threadripper as well. Gigabyte also returned the same info for physical cores, but gave no info on logical ones.
Ultimately that means cores 0-1 are both logically related, cores 0-7 are on the same CCX, and (if on Threadripper) cores 0-15 are on the same die.
This will hopefully help someone else come across the information more quickly and reduce their struggle by some small amount. I hate to cop out, but I'm at work now, so if anyone has an article they feel will supplement this info, please comment it below.