Como ativar 256+ núcleos no Yakkety Server

Question

O Yakkety Server usa o sabor genérico do kernel. É o kernel Linux 4.8.0.

Durante a execução no processador Intel KNL, não consigo ver núcleos acima de 256.

user@ubuntu02:~$ grep processor /proc/cpuinfo | wc -l
256

dmidecode mostra o número real de núcleos

user@ubuntu02:~$ sudo dmidecode -t 4
[sudo] password for user:
# dmidecode 3.0
Getting SMBIOS data from sysfs.
SMBIOS 3.0 present.

Handle 0x001B, DMI type 4, 48 bytes
Processor Information
    Socket Designation: CPU0
    Type: Central Processor
    Family: Xeon
    Manufacturer: Intel(R) Corporation
    ID: 71 06 05 00 FF FB EB BF
    Signature: Type 0, Family 6, Model 87, Stepping 1
    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) Xeon Phi(TM) Processor 000A @ 1.40GHz
    Voltage: 0.9 V
    External Clock: 100 MHz
    Max Speed: 4000 MHz
    Current Speed: 1400 MHz
    Status: Populated, Enabled
    Upgrade: <OUT OF SPEC>
    L1 Cache Handle: 0x0019
    L2 Cache Handle: 0x001A
    L3 Cache Handle: Not Provided
    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: 68
    Core Enabled: 68
    Thread Count: 272
    Characteristics:
            64-bit capable
            Multi-Core
            Hardware Thread
            Execute Protection
            Power/Performance Control

É possível habilitar todos os 272 núcleos sem recompilar o kernel?

user@ubuntu02:~$ grep CONFIG_NR_CPUS /boot/config-4.8.0-32-generic
CONFIG_NR_CPUS=256

Acho que o sabor do kernel do Ubuntu Server deve estar pronto para isso.

    

Answer 1

O número de CPUs foi recentemente aumentado para 512 no kernel Yakkety, e será lançado no kernel Ubuntu-4.8.0-34.35:

commit 4cc43dc6b3bf9ea5b9ed6d91af47dbe137a71cd9
Author: Luis Henriques <[email protected]>
Date:   Thu Dec 8 10:36:14 2016 +0000

    UBUNTU: [Config] Increase the NR_CPUS to 512 for amd64 to support systems with a large number of cores.

    BugLink: http://bugs.launchpad.net/bugs/1579205

    Signed-off-by: Luis Henriques <[email protected]>
    Acked-by: Colin Ian King <[email protected]>
    Acked-by: Tim Gardner <[email protected]>

Então, se você não está rodando esse kernel, atualize e você deve ter essa correção.