如何在Yakkety Server中启用256+个核心

Question

Yakkety Server使用通用内核版本。它是4.8.0的Linux内核。

在Intel KNL处理器上运行时，我无法看到超过256个核心。

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

dmidecode显示真实的核心数

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

可以在不重新编译内核的情况下启用所有272个核心吗？

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

我认为Ubuntu Server的内核版本应该已经准备好了。

- hifly

Answer 1

最近，Yakkety内核的CPU数量已增加到512个，并将在Ubuntu-4.8.0-34.35内核版本中发布。

commit 4cc43dc6b3bf9ea5b9ed6d91af47dbe137a71cd9
Author: Luis Henriques <[e-mail]>
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 <[e-mail]>
    Acked-by: Colin Ian King <[e-mail]>
    Acked-by: Tim Gardner <[e-mail]>

所以，如果你没有运行那个内核，请更新一下，应该就能获得这个修复程序。

- Colin Ian King