Wrong number of cpu cores in /proc/cpuinfo

I am running Ubuntu 18.04 server. I have an Intel i9 9980xe CPU, which has 18 cores and 2 threads per core. But it shows that the CPU has only 15 cores in /proc/cpuinfo as well as in htop. Why?

Here is the part of content in cpuinfo:

processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 85 model name : Intel(R) Core(TM) i9-9980XE CPU @ 3.00GHz stepping : 4 microcode : 0x200005e cpu MHz : 1200.143 cache size : 25344 KB physical id : 0 siblings : 15 core id : 0 cpu cores : 15 apicid : 0 initial apicid : 0 fpu : yes fpu_exception : yes cpuid level : 22 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault cat_l3 cdp_l3 invpcid_single pti ssbd mba ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm cqm mpx rdt_a avx512f avx512dq rdseed adx smap clflushopt clwb intel_pt avx512cd avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local dtherm ida arat pln pts hwp hwp_act_window hwp_pkg_req md_clear flush_l1d bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds bogomips : 6000.00 clflush size : 64 cache_alignment : 64 address sizes : 46 bits physical, 48 bits virtual power management: 

The output of lscpu:

Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian CPU(s): 15 On-line CPU(s) list: 0-14 Thread(s) per core: 1 Core(s) per socket: 15 Socket(s): 1 NUMA node(s): 1 Vendor ID: GenuineIntel CPU family: 6 Model: 85 Model name: Intel(R) Core(TM) i9-9980XE CPU @ 3.00GHz Stepping: 4 CPU MHz: 1200.425 CPU max MHz: 4500.0000 CPU min MHz: 1200.0000 BogoMIPS: 6000.00 Virtualization: VT-x L1d cache: 32K L1i cache: 32K L2 cache: 1024K L3 cache: 25344K NUMA node0 CPU(s): 0-14 Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault cat_l3 cdp_l3 invpcid_single pti ssbd mba ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm cqm mpx rdt_a avx512f avx512dq rdseed adx smap clflushopt clwb intel_pt avx512cd avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local dtherm ida arat pln pts hwp hwp_act_window hwp_pkg_req md_clear flush_l1d 

1 Answer

I solved the above problem. Just because misconfigured the bios.

My colleague installed Win10 on this computer before. However, in the process of installation, he met a "blue screen" error and fixed it through disabling 3 cores of this CPU in bios. That’s the reason why there are only 15 cores shown in my Ubuntu OS.

Thanks for your attention.