安装Ubuntu 14.04后，我的I7 CPU被识别成单核CPU了。

iwasdead · **发表于 :** 2016-06-10 22:12

这个问题非常奇怪，我的电脑是：联想 Lenovo-Rescuer-15ISK

运行lscpu结果：

$ lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 1
On-line CPU(s) list: 0
Thread(s) per core: 1
Core(s) per socket: 1
Socket(s): 1
NUMA node(s): 1
Vendor ID: GenuineIntel
CPU family: 6
Model: 94
Stepping: 3
CPU MHz: 3099.382
BogoMIPS: 5181.65
Virtualization: VT-x
L1d cache: 32K
L1i cache: 32K
L2 cache: 256K
L3 cache: 6144K
NUMA node0 CPU(s): 0

/proc/cpuinfo的结果：
cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 94
model name : Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz
stepping : 3
microcode : 0x23
cpu MHz : 3099.992
cache size : 6144 KB
physical id : 0
siblings : 1
core id : 0
cpu cores : 1
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 arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch ida arat epb pln pts dtherm hwp hwp_noitfy hwp_act_window hwp_epp intel_pt tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm mpx rdseed adx smap clflushopt xsaveopt xsavec xgetbv1
bugs :
bogomips : 5181.65
clflush size : 64
cache_alignment : 64
address sizes : 39 bits physical, 48 bits virtual
power management:

启动参数：
BOOT_IMAGE=/boot/vmlinuz-4.2.0-27-generic.efi.signed root=UUID=99b0156f-8a9b-4cd6-8c6d-0021428f1826 ro acpi=off vt.handoff=7

请高手帮忙看一下这是什么原因？

vickycq · **发表于 :** 2016-06-10 22:43

iwasdead 写道:

启动参数：ro acpi=off vt.handoff=7

可能原因使用了内核参数 acpi=off

执行以下指令将结果全部复制贴上来

代码:

uname -a
dmesg | grep -i smp

参考
http://www.linuxquestions.org/questions/linux-kernel-70/smp-kernel-and-acpi%3Doff-614311/
http://unix.stackexchange.com/questions/56703/kernel-not-detecting-multicore-cpu
http://askubuntu.com/questions/340517/how-do-i-enable-all-four-cores-on-my-toshiba-p70-a-notebook-only-one-enabled-n
http://askubuntu.com/questions/127815/using-quad-core-but-only-1-cpu-entry-in-proc-cpuinfo-is-smp-running-on-my-c
https://bbs.archlinux.org/viewtopic.php?id=70156
http://askubuntu.com/questions/116757/ubuntu-server-11-04-recognize-only-1-core-instead-of-4

iwasdead · **发表于 :** 2016-06-10 23:09

谢谢 vickycq

加入这个选项是因为如果不加入acpi=off的话，ubuntu系统根本就无法启动。

uname -a

代码:

Linux nigang-Lenovo-Rescuer-15ISK 4.2.0-27-generic #32~14.04.1-Ubuntu SMP Fri Jan 22 15:32:26 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

代码:

[    0.000000] Linux version 4.2.0-27-generic (buildd@lcy01-23) (gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1) ) #32~14.04.1-Ubuntu SMP Fri Jan 22 15:32:26 UTC 2016 (Ubuntu 4.2.0-27.32~14.04.1-generic 4.2.8-ckt1)
[    0.000000] smpboot: Allowing 1 CPUs, 0 hotplug CPUs
[    0.014272] Freeing SMP alternatives memory: 28K (ffffffff81ea7000 - ffffffff81eae000)
[    0.028670] smpboot: weird, boot CPU (#0) not listed by the BIOS
[    0.028671] smpboot: SMP motherboard not detected
[    0.028672] smpboot: SMP disabled
[    0.029430] smpboot: Total of 1 processors activated (5181.65 BogoMIPS)

dmidecode

代码:

Handle 0x0004, DMI type 4, 42 bytes
Processor Information
   Socket Designation: U3E1
   Type: Central Processor
   Family: Core i7
   Manufacturer: Intel(R) Corporation
   ID: E3 06 05 00 FF FB EB BF
   Signature: Type 0, Family 6, Model 94, Stepping 3
   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)
      DS (Debug store)
      ACPI (ACPI supported)
      MMX (MMX technology supported)
      FXSR (FXSAVE and FXSTOR instructions supported)
      SSE (Streaming SIMD extensions)
      SSE2 (Streaming SIMD extensions 2)
      SS (Self-snoop)
      HTT (Multi-threading)
      TM (Thermal monitor supported)
      PBE (Pending break enabled)
   Version: Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz
   Voltage: 0.9 V
   External Clock: 100 MHz
   Max Speed: 2600 MHz
   Current Speed: 2500 MHz
   Status: Populated, Enabled
   Upgrade: Other
   L1 Cache Handle: 0x0006
   L2 Cache Handle: 0x0007
   L3 Cache Handle: 0x0008
   Serial Number: To Be Filled By O.E.M.
   Asset Tag: To Be Filled By O.E.M.
   Part Number: To Be Filled By O.E.M.
   Core Count: 4
   Core Enabled: 4
   Thread Count: 8
   Characteristics:
      64-bit capable
      Multi-Core
      Hardware Thread
      Execute Protection
      Enhanced Virtualization
      Power/Performance Control

vickycq · **发表于 :** 2016-06-11 12:55

iwasdead 写道:

4.2.0-27-generic #32~14.04.1-Ubuntu SMP Fri Jan 22 15:32:26 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

目前使用的内核支持 SMP

iwasdead 写道:

[ 0.028672] smpboot: SMP disabled
[ 0.029430] smpboot: Total of 1 processors activated (5181.65 BogoMIPS)

SMP 遭到禁用
可能原因使用了 acpi=off

iwasdead 写道:

如果不加入acpi=off的话，ubuntu系统根本就无法启动。

安装其它版本的内核 (4.4, 4.5, 4.6) 试试
或其它版本的Ubuntu (16.04) 试试
或其它发行版 (Fedora 24 beta, archlinux, Debian sid, openSUSE 42.1) 试试
或以 2 楼诸参考链接为基础，多多调研相关情况试试

photor · **发表于 :** 2016-06-11 17:23

iwasdead · **发表于 :** 2016-06-20 9:15

谢谢了，楼主。
我用最新的kernel就OK了。

安装Ubuntu 14.04后，我的I7 CPU被识别成单核CPU了。

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