Just got a new server, has 2 x AMD epyc processors 16 cores each.
They are multi-thread capable
# dmidecode -t processor | grep HTT
HTT (Multi-threading)
HTT (Multi-threading)
but it appears to be off - fresh installation of 20.04
# lscpu | grep Thread
Thread(s) per core: 1
How do I turn multi-threading on?
additional info someone asked for:
# nproc; numactl -s; cat /proc/cpuinfo | grep processor
32
policy: default
preferred node: current
physcpubind: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
cpubind: 0 1 2 3 4 5 6 7
nodebind: 0 1 2 3 4 5 6 7
membind: 0 1 2 3 4 5 6 7
processor : 0
processor : 1
processor : 2
processor : 3
processor : 4
processor : 5
processor : 6
processor : 7
processor : 8
processor : 9
processor : 10
processor : 11
processor : 12
processor : 13
processor : 14
processor : 15
processor : 16
processor : 17
processor : 18
processor : 19
processor : 20
processor : 21
processor : 22
processor : 23
processor : 24
processor : 25
processor : 26
processor : 27
processor : 28
processor : 29
processor : 30
processor : 31
To be clear because someone below asked, HTT (AMD multithreading) is where one physical core is presented to the OS user as two virtual cores. Here is an example of a DIFFERENT MACHINE where it is working correctly. As you can see there is one physical CPU (physical id=0), with 16 physical cores (core id), but presented as 32 cores to the OS (for example core 3 being processor 3 and processor 19).
# cat /proc/cpuinfo | egrep '(core id|physical id|processor)' | paste -d "\t" - - -
processor : 0 physical id : 0 core id : 0
processor : 1 physical id : 0 core id : 1
processor : 2 physical id : 0 core id : 2
processor : 3 physical id : 0 core id : 3
processor : 4 physical id : 0 core id : 4
processor : 5 physical id : 0 core id : 5
processor : 6 physical id : 0 core id : 6
processor : 7 physical id : 0 core id : 7
processor : 8 physical id : 0 core id : 8
processor : 9 physical id : 0 core id : 9
processor : 10 physical id : 0 core id : 10
processor : 11 physical id : 0 core id : 11
processor : 12 physical id : 0 core id : 12
processor : 13 physical id : 0 core id : 13
processor : 14 physical id : 0 core id : 14
processor : 15 physical id : 0 core id : 15
processor : 16 physical id : 0 core id : 0
processor : 17 physical id : 0 core id : 1
processor : 18 physical id : 0 core id : 2
processor : 19 physical id : 0 core id : 3
processor : 20 physical id : 0 core id : 4
processor : 21 physical id : 0 core id : 5
processor : 22 physical id : 0 core id : 6
processor : 23 physical id : 0 core id : 7
processor : 24 physical id : 0 core id : 8
processor : 25 physical id : 0 core id : 9
processor : 26 physical id : 0 core id : 10
processor : 27 physical id : 0 core id : 11
processor : 28 physical id : 0 core id : 12
processor : 29 physical id : 0 core id : 13
processor : 30 physical id : 0 core id : 14
processor : 31 physical id : 0 core id : 15
