我们正在从 Ubuntu 18.04 升级到 22.04m5a.大号AWS 系统（两个 vCPU）。我们安装了GNU 并行来自 Ubuntu 仓库。
在 Ubuntu 18.04 上：
# parallel --number-of-cores
2
在 Ubuntu 22.04 上：
# parallel --number-of-cores
1
再次强调，这两者都m5a.大号实例（2 个 vCPU）。
知道为什么并行无法识别第二个 CPU 吗？
有关 Ubuntu 22.04 系统的更多数据。大多数系统显示 2 个核心，但有些系统只显示 1 个核心。例如：
lscpu显示 2 个 CPU：
# lscpu | egrep CPU
CPU op-mode(s): 32-bit, 64-bit
CPU(s): 2
On-line CPU(s) list: 0,1
CPU family: 23
NUMA node0 CPU(s): 0,1
/proc/cpuinfo显示2：
# cat /proc/cpuinfo |egrep processor
processor : 0
processor : 1
nproc显示2：
# nproc
2
dmidecode仅显示1：
# dmidecode -t processor | egrep -i "cpu|core"
Socket Designation: CPU 0
Core Count: 1
Core Enabled: 1
Multi-Core
getconf显示2：
# getconf _NPROCESSORS_ONLN
2
更新：如下所述，完整的 cpuinfo 和 lscpu。
cpuinfo:
processor : 0
vendor_id : AuthenticAMD
cpu family : 23
model : 1
model name : AMD EPYC 7571
stepping : 2
microcode : 0x800126e
cpu MHz : 2199.738
cache size : 512 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 1
apicid : 0
initial apicid : 0
fpu : yes
fpu_exception : yes
cpuid level : 13
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc cpuid extd_apicid aperfmperf tsc_known_freq pni pclmulqdq ssse3 fma cx16 sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm cmp_legacy cr8_legacy abm sse4a misalignsse 3dnowprefetch topoext vmmcall fsgsbase bmi1 avx2 smep bmi2 rdseed adx smap clflushopt sha_ni xsaveopt xsavec xgetbv1 clzero xsaveerptr arat npt nrip_save
bugs : sysret_ss_attrs null_seg spectre_v1 spectre_v2 spec_store_bypass retbleed smt_rsb srso div0
bogomips : 4399.47
TLB size : 2560 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 48 bits physical, 48 bits virtual
power management:
processor : 1
vendor_id : AuthenticAMD
cpu family : 23
model : 1
model name : AMD EPYC 7571
stepping : 2
microcode : 0x800126e
cpu MHz : 2199.738
cache size : 512 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 1
apicid : 1
initial apicid : 1
fpu : yes
fpu_exception : yes
cpuid level : 13
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc cpuid extd_apicid aperfmperf tsc_known_freq pni pclmulqdq ssse3 fma cx16 sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm cmp_legacy cr8_legacy abm sse4a misalignsse 3dnowprefetch topoext vmmcall fsgsbase bmi1 avx2 smep bmi2 rdseed adx smap clflushopt sha_ni xsaveopt xsavec xgetbv1 clzero xsaveerptr arat npt nrip_save
bugs : sysret_ss_attrs null_seg spectre_v1 spectre_v2 spec_store_bypass retbleed smt_rsb srso div0
bogomips : 4399.47
TLB size : 2560 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 48 bits physical, 48 bits virtual
power management:
lscppu：
Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Address sizes: 48 bits physical, 48 bits virtual Byte Order: Little Endian CPU(s): 2 On-line CPU(s) list: 0,1 Vendor ID: AuthenticAMD Model name: AMD EPYC 7571
CPU family: 23
Model: 1
Thread(s) per core: 2
Core(s) per socket: 1
Socket(s): 1
Stepping: 2
BogoMIPS: 4399.47
Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nons
top_tsc cpuid extd_apicid aperfmperf tsc_known_freq pni pclmulqdq ssse3 fma cx16 sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm cmp_legacy cr8_legacy ab
m sse4a misalignsse 3dnowprefetch topoext vmmcall fsgsbase bmi1 avx2 smep bmi2 rdseed adx smap clflushopt sha_ni xsaveopt xsavec xgetbv1 clzero xsaveerptr arat npt nrip_save Virtualization features: Hypervisor vendor: KVM Virtualization type: full Caches (sum of all): L1d: 32 KiB (1 instance) L1i: 64 KiB (1 instance) L2: 512 KiB (1 instance) L3: 8 MiB (1 instance) NUMA: NUMA node(s): 1 NUMA node0 CPU(s): 0,1 Vulnerabilities: Gather data sampling: Not affected Itlb multihit: Not affected L1tf: Not affected Mds: Not affected Meltdown: Not affected Mmio stale data: Not affected Retbleed: Mitigation; untrained return thunk; SMT vulnerable Spec rstack overflow: Mitigation; safe RET, no microcode Spec store bypass: Vulnerable Spectre v1: Mitigation; usercopy/swapgs barriers and __user pointer sanitization Spectre v2: Mitigation; Retpolines, STIBP disabled, RSB filling, PBRSB-eIBRS Not affected Srbds: Not affected Tsx async abort: Not affected
但我认为真正的问题在于 dmidecode，它只显示一个 CPU。dmidecode -t 处理器：
# dmidecode 3.3
Getting SMBIOS data from sysfs.
SMBIOS 2.7 present.
Handle 0x0004, DMI type 4, 42 bytes
Processor Information
Socket Designation: CPU 0
Type: Central Processor
Family: Zen
Manufacturer: Advanced Micro Devices, Inc.
ID: 12 0F 80 00 FF FB 8B 17
Signature: Family 23, Model 1, Stepping 2
Flags:
FPU (Floating-point unit on-chip)
VME (Virtual mode extension)
DE (Debugging extension)
PSE (Page size extension)
TSC (Time stamp counter)
MSR (Model specific registers)
PAE (Physical address extension)
MCE (Machine check exception)
CX8 (CMPXCHG8 instruction supported)
APIC (On-chip APIC hardware supported)
SEP (Fast system call)
MTRR (Memory type range registers)
PGE (Page global enable)
MCA (Machine check architecture)
CMOV (Conditional move instruction supported)
PAT (Page attribute table)
PSE-36 (36-bit page size extension)
CLFSH (CLFLUSH instruction supported)
MMX (MMX technology supported)
FXSR (FXSAVE and FXSTOR instructions supported)
SSE (Streaming SIMD extensions)
SSE2 (Streaming SIMD extensions 2)
HTT (Multi-threading)
Version: AMD EPYC 7571
Voltage: 1.0 V
External Clock: 100 MHz
Max Speed: 3000 MHz
Current Speed: 2200 MHz
Status: Populated, Enabled
Upgrade: Socket SP3
L1 Cache Handle: 0x0005
L2 Cache Handle: 0x0006
L3 Cache Handle: 0x0007
Serial Number: Not Specified
Asset Tag: Not Specified
Part Number: Not Specified
Core Count: 1
Core Enabled: 1
Thread Count: 2
Characteristics:
64-bit capable
Multi-Core
Hardware Thread
Execute Protection