AMD EPYC 7551p CPU Pinning

[PapaGigas]

Hi,

I'm using an AMD EPYC 7551p CPU with 4 physical dies and 8 cores per physical die (32 cores and 64 threads) and 8 DDR4 ECC RAM modules with 16GB each (128GB).

I want to run all my VM's inside each physical die (and make sure that they use only the RAM modules directly assigned to them) in order to avoid any performance issue.

---------- [ Physical die 1 ] ----------

- Proxmox VE (2 Cores + 8GB)

- VM1 (2 Cores + 8GB)

- VM2 (2 Cores + 8GB)

- VM3 (2 Cores + 8GB)

---------- [ Physical die 2 ] ----------

- VM4 (4 Cores + 16GB)

- VM5 (4 Cores + 16GB)

---------- [ Physical die 3 ] ----------

- VM6 (4 Cores + 16GB)

- VM7 (4 Cores + 16GB)

---------- [ Physical die 4 ] ----------

- VM8 (4 Cores + 16GB)

- VM9 (4 Cores + 16GB)

Is it possible to pin all my 9 VM's (that run 24/7) like this, leaving 2 cores and 8GB of RAM available for Proxmox VE?

 

[Falk R.]

Don’t use pinning, the automatic CPU scheduler are better than any manual configuration.

 

[PapaGigas]

Don’t use pinning, the automatic CPU scheduler are better than any manual configuration.

Will it always avoid AMD's Infinity Fabric and make sure the VM's use only one of the physical dies?

 

[Falk R.]

I don’t know, but at Benchmarks, you have less CPU Latency with Epyc CPUs. A Big difference is, when you use multiple Sockets, you must configure Numa aware.

 

[PapaGigas]

I don’t know, but at Benchmarks, you have less CPU Latency with Epyc CPUs. A Big difference is, when you use multiple Sockets, you must configure Numa aware.

Wouldn't it be better like this in order to avoid performance issues with AMD's Infinity Fabric?

-------------------------------------------------- [ Die 1 ] --------------------------------------------------

PVE (2 Cores + 8GB/RAM) -> CCX 1: 0/32, 1/33 [reserved]

101 (2 Cores + 8GB/RAM) -> CCX 1: 2/34, 3/35 [pinned]

102 (2 Cores + 8GB/RAM) -> CCX 2: 4/36, 5/37 [pinned]

103 (2 Cores + 8GB/RAM) -> CCX 2: 6/38, 7/39 [pinned]

-------------------------------------------------- [ Die 2 ] --------------------------------------------------

104 (4 Cores + 16GB/RAM) -> CCX 3: 8/40, 9/41, 10/42, 11/43 [pinned]

105 (4 Cores + 16GB/RAM) -> CCX 4: 12/44, 13/45, 14/46, 15/47 [pinned]

-------------------------------------------------- [ Die 3 ] --------------------------------------------------

106 (4 Cores + 16GB/RAM) -> CCX 5: 16/48, 17/49, 18/50, 19/51 [pinned]

107 (4 Cores + 16GB/RAM) -> CCX 6: 20/52, 21/53, 22/54, 23/55 [pinned]

-------------------------------------------------- [ Die 4 ] --------------------------------------------------

108 (4 Cores + 16GB/RAM) -> CCX 7: 24/56, 25/57, 26/58, 27/59 [pinned]

109 (4 Cores + 16GB/RAM) -> CCX 8: 28/60, 29/61, 30/62, 31/63 [pinned]