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--- | ||
approvers: | ||
- vishh | ||
title: 调度 GPU | ||
--- | ||
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{% capture overview %} | ||
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Kubernetes 提供对分布在节点上的 NVIDIA GPU 进行管理的**实验**支持。本页描述用户如何使用 GPU 以及当前使用的一些限制 | ||
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{% endcapture %} | ||
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{% capture prerequisites %} | ||
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1. Kubernetes 节点必须预先安装好 NVIDIA 驱动,否则,Kubelet 将检测不到可用的GPU信息;如果节点的 Capacity 属性中没有出现 NIVIDA GPU 的数量,有可能是驱动没有安装或者安装失败,请尝试重新安装 | ||
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2. 在整个 Kubernetes 系统中,feature-gates 里面特定的 **alpha** 特性参数 `Accelerators` 必须设置为 true:`--feature-gates="Accelerators=true"` | ||
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3. Kuberntes 节点必须使用 `docker` 引擎作为容器的运行引擎 | ||
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上述预备工作完成后,节点会自动发现它上面的 NVIDIA GPU,并将其作为可调度资源暴露 | ||
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{% endcapture %} | ||
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{% capture steps %} | ||
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## API | ||
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容器可以通过名称为 `alpha.kubernetes.io/nvidia-gpu` 的标识来申请需要使用的 NVIDIA GPU 的数量 | ||
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```yaml | ||
apiVersion: v1 | ||
kind: Pod | ||
metadata: | ||
name: gpu-pod | ||
spec: | ||
containers: | ||
- | ||
name: gpu-container-1 | ||
image: gcr.io/google_containers/pause:2.0 | ||
resources: | ||
limits: | ||
alpha.kubernetes.io/nvidia-gpu: 2 # requesting 2 GPUs | ||
- | ||
name: gpu-container-2 | ||
image: gcr.io/google_containers/pause:2.0 | ||
resources: | ||
limits: | ||
alpha.kubernetes.io/nvidia-gpu: 3 # requesting 3 GPUs | ||
``` | ||
- GPU 只能在容器资源的 `limits` 中配置 | ||
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- 容器和 Pod 都不支持共享 GPU | ||
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- 每个容器可以申请使用一个或者多个 GPU | ||
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- GPU 必须以整数为单位被申请使用 | ||
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- 所有节点的 GPU 硬件要求相同 | ||
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如果在不同的节点上面安装了不同版本的 GPU,可以通过设置节点标签以及使用节点选择器的方式将 pod 调度到期望运行的节点上。工作流程如下: | ||
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在节点上,识别出 GPU 硬件类型,然后将其作为节点标签进行暴露 | ||
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```shell | ||
NVIDIA_GPU_NAME=$(nvidia-smi --query-gpu=gpu_name --format=csv,noheader --id=0) | ||
source /etc/default/kubelet | ||
KUBELET_OPTS="$KUBELET_OPTS --node-labels='alpha.kubernetes.io/nvidia-gpu-name=$NVIDIA_GPU_NAME'" | ||
echo "KUBELET_OPTS=$KUBELET_OPTS" > /etc/default/kubelet | ||
``` | ||
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在 pod 上,通过节点[亲和性](/docs/concepts/configuration/assign-pod-node/#affinity-and-anti-affinity)规则为它指定可以使用的 GPU 类型 | ||
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```yaml | ||
kind: pod | ||
apiVersion: v1 | ||
metadata: | ||
annotations: | ||
scheduler.alpha.kubernetes.io/affinity: > | ||
{ | ||
"nodeAffinity": { | ||
"requiredDuringSchedulingIgnoredDuringExecution": { | ||
"nodeSelectorTerms": [ | ||
{ | ||
"matchExpressions": [ | ||
{ | ||
"key": "alpha.kubernetes.io/nvidia-gpu-name", | ||
"operator": "In", | ||
"values": ["Tesla K80", "Tesla P100"] | ||
} | ||
] | ||
} | ||
] | ||
} | ||
} | ||
} | ||
spec: | ||
containers: | ||
- | ||
name: gpu-container-1 | ||
resources: | ||
limits: | ||
alpha.kubernetes.io/nvidia-gpu: 2 | ||
``` | ||
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上述设定可以确保 pod 会被调度到包含名称为 `alpha.kubernetes.io/nvidia-gpu-name` 的标签并且标签的值为 `Tesla K80` 或者 `Tesla P100` 的节点上 | ||
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### 警告 | ||
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当未来的 Kubernetes 版本能够更好的支持GPU以及一般的硬件加速器时,这里的 API 描述**将会随之做出变更** | ||
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## 访问 CUDA 库 | ||
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到目前为止,还需要预先在节点上安装 CUDA 库 | ||
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为了避免后面使用库出现问题,可以将库放到 ``/var/lib/`` 下的某个文件夹下,或者直接改变库目录的权限(以后的版本会自动完成这一过程) | ||
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Pods能够通过 `hostPath` 卷来访问库 | ||
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```yaml | ||
kind: Pod | ||
apiVersion: v1 | ||
metadata: | ||
name: gpu-pod | ||
spec: | ||
containers: | ||
- name: gpu-container-1 | ||
image: gcr.io/google_containers/pause:2.0 | ||
resources: | ||
limits: | ||
alpha.kubernetes.io/nvidia-gpu: 1 | ||
volumeMounts: | ||
- mountPath: /usr/local/nvidia/bin | ||
name: bin | ||
- mountPath: /usr/lib/nvidia | ||
name: lib | ||
volumes: | ||
- hostPath: | ||
path: /usr/lib/nvidia-375/bin | ||
name: bin | ||
- hostPath: | ||
path: /usr/lib/nvidia-375 | ||
name: lib | ||
``` | ||
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## 未来 | ||
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- Kubernetes 对硬件加速器的支持还处在早期阶段 | ||
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- GPU 和其它的加速器很快会成为系统的本地计算资源 | ||
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- 将引入更好的 API 以可扩展的方式提供和使用加速器 | ||
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- Kubernets 将会自动确保应用在使用 GPU 时得到最佳性能 | ||
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- 类似访问 CUDA 库这种关键的可用性问题将得到解决 | ||
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{% endcapture %} | ||
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{% include templates/task.md %} |