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如何在虚拟环境中启用多个核心？

tag-icon • tag-icon 12.04 virtualbox oracle virtualization multi-core
如何在虚拟环境中启用多个核心？

我已经使用 Oracle VM VirtualBox Manager 在虚拟环境中安装了 Ubuntu，并且运行良好。

不过我想启用多个核心 - 如下图所示，我的 Windows 机器有 2 个核心：

在此处输入图片描述

现在，当我在 Ubuntu 中运行时，lscpu我收到以下信息，显示仅使用了 1 个核心：

在此处输入图片描述

我尝试更改虚拟框的设置以启用多个处理器，但它不允许我这样做，如下图所示：

图像

如何在我的虚拟环境中启用多个核心（处理器）？

答案1

要在您的虚拟机中启用超过 1 个 CPU，还需要进行以下设置：

  • 常规设置选项卡中的 64 位虚拟客户机硬件（适用于 64 位客户机）

    在此处输入图片描述

  • 在主板设置选项卡中启用 I/O APIC

    在此处输入图片描述

  • 在“加速”选项卡中启用硬件虚拟化（VT-x / AMD-V）

    在此处输入图片描述

请注意，如果您在所有可用核心上运行虚拟机，则在为 CPU 分配执行上限时您可能会体验到更好的主机性能。

如果您尚未启用热插拔 CPU虚拟机更改核心数的功能只能在关闭。

只有使用多核的软件才能在客户机上实现性能提升。只有这样，为所有核心提供执行上限才有意义。

答案2

如果您的虚拟机当前正在运行（或“已保存”），则您无法更改该值。请先关闭虚拟机。

答案3

我正在开发一个在虚拟机上按顺序执行的多线程程序。我遇到了和你类似的问题。我通过以下方式修复了它：

  1. 停止虚拟机或者退出。
  2. 启动 VMWare --> 选择机器 --> 单击系统 --> 单击处理器 --> 更改处理器数量。
  3. 启动虚拟机。

以前，标准线程中的 std::thread::hardware_concurrency() 返回 1，但是，经过更改后，它会返回虚拟机设置上的 CPU 数量。

现在，我能够在 VM 上成功运行我的多线程程序。

答案4

其他答案对我来说不起作用，所以我分享了我的解决方案，该解决方案基于VirtualBox 手册 §2.4 CPU 热插拔。

GUI 允许我添加 32 个 vCPU，但 Linux 客户机启动时nproc只会cat /proc/cpuinfo显示一个 CPU/核心/线程。我可以看到dmesg检测到了 32 个 vCPU：

# dmesg | grep -E 'smp:|smpboot:'
[    0.000000] smpboot: Allowing 32 CPUs, 31 hotplug CPUs
[    0.192151] smpboot: CPU0: Intel(R) Xeon(R) Gold 6148 CPU @ 2.40GHz (family: 0x6, model: 0x55, stepping: 0x4)
[    0.193848] smp: Bringing up secondary CPUs ...
[    0.193850] smp: Brought up 1 node, 1 CPU
[    0.193852] smpboot: Max logical packages: 32
[    0.193854] smpboot: Total of 1 processors activated (4788.97 BogoMIPS)

似乎热插拔已启用，但由于某种原因 CPU 未在线。

在主机上运行以下命令：

for i in {1..31}; do VBoxManage controlvm $VM plugcpu $i; done

从客户机内部我可以看到 CPU 已经热插拔，但它们不会自动上线：

# dmesg | grep 'has been hot-added'
[  317.236099] CPU1 has been hot-added
[  317.289383] CPU2 has been hot-added
[  317.341704] CPU3 has been hot-added
[  317.393434] CPU4 has been hot-added
[  317.602969] CPU5 has been hot-added
[  317.603570] CPU6 has been hot-added
[  317.603810] CPU7 has been hot-added
[  317.604031] CPU8 has been hot-added
[  317.780191] CPU9 has been hot-added
[  317.780498] CPU10 has been hot-added
[  317.780745] CPU11 has been hot-added
[  317.817875] CPU12 has been hot-added
[  317.870629] CPU13 has been hot-added
[  317.911276] CPU14 has been hot-added
[  317.962533] CPU15 has been hot-added
[  318.012838] CPU16 has been hot-added
[  318.063693] CPU17 has been hot-added
[  318.116346] CPU18 has been hot-added
[  318.167847] CPU19 has been hot-added
[  318.232230] CPU20 has been hot-added
[  318.284266] CPU21 has been hot-added
[  318.344941] CPU22 has been hot-added
[  318.373422] CPU23 has been hot-added
[  318.501419] CPU24 has been hot-added
[  318.501714] CPU25 has been hot-added
[  318.535717] CPU26 has been hot-added
[  318.652636] CPU27 has been hot-added
[  318.653046] CPU28 has been hot-added
[  318.689386] CPU29 has been hot-added
[  318.739736] CPU30 has been hot-added
[  318.790743] CPU31 has been hot-added

# nproc
6

但是您可以通过运行以下命令在客户机中手动使 CPU 联机：

# for CPU in /sys/devices/system/cpu/cpu*/online; do echo 1 | sudo tee $CPU >/dev/null; done

健康：

# nproc
32

当客户机重新启动时，这种情况似乎仍然存在：

# dmesg | grep -E 'smp:|smpboot:'
[    0.000000] smpboot: Allowing 32 CPUs, 0 hotplug CPUs
[    0.189487] smpboot: CPU0: Intel(R) Xeon(R) Gold 6148 CPU @ 2.40GHz (family: 0x6, model: 0x55, stepping: 0x4)
[    0.191502] smp: Bringing up secondary CPUs ...
[    0.278723] smp: Brought up 1 node, 32 CPUs
[    0.278723] smpboot: Max logical packages: 1
[    0.278723] smpboot: Total of 32 processors activated (153236.67 BogoMIPS)

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