gpu_nfdhook

README

Intel GPU NFD hook

Table of Contents

• Introduction
• GPU memory
• Default labels
• PCI-groups (optional)
• Capability labels (optional)
• Limitations

Introduction

This is the Node Feature Discovery binary hook implementation for the Intel GPUs. The intel-gpu-initcontainer (which is built with the other images) can be used as part of the gpu-plugin deployment to copy hook to the host systems on which gpu-plugin itself is deployed.

When NFD worker runs this hook, it will add a number of labels to the nodes, which can be used for example to deploy services to nodes with specific GPU types. Selected numeric labels can be turned into kubernetes extended resources by the NFD, allowing for finer grained resource management for GPU-using PODs.

In the NFD deployment, the hook requires /host-sys -folder to have the host /sys-folder content mounted. Write access is not necessary.

GPU memory

GPU memory amount is read from sysfs gt/gt* files and turned into a label. There are two supported environment variables named GPU_MEMORY_OVERRIDE and GPU_MEMORY_RESERVED. Both are supposed to hold numeric byte amounts. For systems with older kernel drivers or GPUs which do not support reading the GPU memory amount, the GPU_MEMORY_OVERRIDE environment variable value is turned into a GPU memory amount label instead of a read value. GPU_MEMORY_RESERVED value will be scoped out from the GPU memory amount found from sysfs.

Default labels

Following labels are created by default. You may turn numeric labels into extended resources with NFD.

name	type	description
gpu.intel.com/millicores	number	node GPU count * 1000. Can be used as a finer grained shared execution fraction.
gpu.intel.com/memory.max	number	sum of detected GPU memory amounts in bytes OR environment variable value * GPU count
gpu.intel.com/cards	string	list of card names separated by '.'. The names match host card*-folders under /sys/class/drm/. Deprecated, use gpu-numbers.
gpu.intel.com/gpu-numbers	string	list of numbers separated by '.'. The numbers correspond to device file numbers for the primary nodes of given GPUs in kernel DRI subsystem, listed as /dev/dri/card<num> in devfs, and /sys/class/drm/card<num> in sysfs.
gpu.intel.com/tiles	number	sum of all detected GPU tiles in the system.
gpu.intel.com/numa-gpu-map	string	list of numa node to gpu mappings.

If the value of the gpu-numbers label would not fit into the 63 character length limit, you will also get labels gpu-numbers2, gpu-numbers3... until all the gpu numbers have been labeled.

The tile count gpu.intel.com/tiles describes the total amount of tiles on the system. System is expected to be homogeneous, and thus the number of tiles per GPU can be calculated by dividing the tile count with GPU count.

The numa-gpu-map label is a list of numa to gpu mapping items separated by _. Each list item has a numa node id combined with a list of gpu indices. e.g. 0-1.2.3 would mean: numa node 0 has gpus 1, 2 and 3. More complex example would be: 0-0.1_1-3.4 where numa node 0 would have gpus 0 and 1, and numa node 1 would have gpus 3 and 4. As with gpu-numbers, this label will be extended to multiple labels if the length of the value exceeds the max label length.

PCI-groups (optional)

GPUs which share the same pci paths under /sys/devices/pci* can be grouped into a label. GPU nums are separated by '.' and groups are separated by '_'. The label is created only if environment variable named GPU_PCI_GROUPING_LEVEL has a value greater than zero. GPUs are considered to belong to the same group, if as many identical folder names are found for the GPUs, as is the value of the environment variable. Counting starts from the folder name which starts with pci.

For example, the SG1 card has 4 GPUs, which end up sharing pci-folder names under /sys/devices. With a GPU_PCI_GROUPING_LEVEL of 3, a node with two such SG1 cards could produce a pci-groups label with a value of 0.1.2.3_4.5.6.7.

name	type	description
gpu.intel.com/pci-groups	string	list of pci-groups separated by '_'. GPU numbers in the groups are separated by '.'. The numbers correspond to device file numbers for the primary nodes of given GPUs in kernel DRI subsystem, listed as /dev/dri/card<num> in devfs, and /sys/class/drm/card<num> in sysfs.

If the value of the pci-groups label would not fit into the 63 character length limit, you will also get labels pci-groups2, pci-groups3... until all the pci groups have been labeled.

Capability labels (optional)

Capability labels are created from information found inside debugfs, and therefore unfortunately require running the NFD worker as root. Due to coming from debugfs, which is not guaranteed to be stable, these are not guaranteed to be stable either. If you do not need these, simply do not run NFD worker as root, that is also more secure. Depending on your kernel driver, running the NFD hook as root may introduce following labels:

name	type	description
gpu.intel.com/platform_gen	string	GPU platform generation name, typically an integer. Deprecated.
gpu.intel.com/media_version	string	GPU platform Media pipeline generation name, typically a number. Deprecated.
gpu.intel.com/graphics_version	string	GPU platform graphics/compute pipeline generation name, typically a number. Deprecated.
gpu.intel.com/platform_<PLATFORM_NAME>.count	number	GPU count for the named platform.
gpu.intel.com/platform_<PLATFORM_NAME>.tiles	number	GPU tile count in the GPUs of the named platform.
gpu.intel.com/platform_<PLATFORM_NAME>.present	string	"true" for indicating the presense of the GPU platform.

Limitations

For the above to work as intended, GPUs on the same node must be identical in their capabilities.