GPU device selection

GPU device selection#

This page describes GPU device selection on a multi-GPU system.

1. Media (VAAPI based) elements#

GStreamer VAAPI plugin supports environment variable GST_VAAPI_DRM_DEVICE which allows to select GPU device for VAAPI elements (and decodebin3 element in case it internally works on VAAPI elements).

The environment variable GST_VAAPI_DRM_DEVICE expects GPU device driver path, the path /dev/dri/renderD128 typically represents first GPU device on system, /dev/dri/renderD129 represents second GPU device on system, etc.

For example, the following command forces VAAPI elements (and decodebin3) to use second GPU device

export GST_VAAPI_DRM_DEVICE=/dev/dri/renderD129

2. Inference (OpenVINO™ based) elements#

Explicit selection#

In case of video decode running on CPU and inference running on GPU, the device property in inference elements allows to select GPU device according to OpenVINO™ GPU device naming with devices enumerated as “GPU.0”, “GPU.1”, etc, for example:

gst-launch-1.0 "... ! decodebin3 ! gvadetect device=GPU.1 ! ..."

Automatic selection#

In case of both video decode and inference running on GPU, select GPU device via setting environment variable for VAAPI decode element, and set device=GPU for all inference elements. It allows inference elements to query VAAPI context from VAAPI decode element and automatically run inference and pre-processing on same GPU device as video decode (GPU device affinity). For example (selecting second GPU device for decode and inference):

export GST_VAAPI_DRM_DEVICE=/dev/dri/renderD129
gst-launch-1.0 "... ! decodebin3 ! gvadetect device=GPU ! ..."

3. Media and Inference elements for GStreamer 1.24.0 and later versions#

Note

Starting with GStreamer 1.24 version GStreamer-VAAPI should be considered deprecated in favor of the GstVA plugin.

The GST_VAAPI_ALL_DRIVERS environment variable is deprecated in favor of GST_VA_ALL_DRIVERS.

As stated earlier, the GStreamer framework allows selecting the GPU render device for VA codecs plugins if there is more than one GPU device on the system.

For single-GPU device systems, the VA codecs plugin element like vah264dec, vapostproc, etc., corresponds to

  • GPU (GPU.0) device -> /dev/dri/renderD128

For multi-GPU device systems, each additional GPU device corresponds to a separate DRI device. e.g.

  • GPU.1 -> /dev/dri/renderD129

  • GPU.2 -> /dev/dri/renderD130 etc.

The command below lists the available VA codecs plugins on the system for each GPU device

gst-inspect-1.0 | grep va
. . .
va:  vah264dec: VA-API H.264 Decoder in Intel(R) Gen Graphics
va:  vapostproc: VA-API Video Postprocessor in Intel(R) Gen Graphics
. . .
va:  varenderD129h264dec: VA-API H.264 Decoder in Intel(R) Gen Graphics in renderD129
va:  varenderD129postproc: VA-API Video Postprocessor in Intel(R) Gen Graphics in renderD129
. . .
va:  varenderD130h265dec: VA-API H.265 Decoder in Intel(R) Gen Graphics in renderD130
va:  varenderD130postproc: VA-API Video Postprocessor in Intel(R) Gen Graphics in renderD130

Example of GPU.0 and coresponding VA codec elements, e.g. vah264dec and vapostproc usage:

gst-launch-1.0 filesrc location=${VIDEO_FILE} ! parsebin ! vah264dec ! vapostproc ! "video/x-raw(memory:VAMemory)" ! \
gvadetect model=${MODEL_FILE} device=GPU.0 pre-process-backend=va-surface-sharing batch_size=8 ! queue ! gvafpscounter ! fakesink

For GPU devices other than the default one (i.e. GPU or GPU.0) the renderD1XY element component selects assigned GPU device e.g.:

  • GPU.1 -> varenderD129h264dec, varenderD129postproc

  • GPU.2 -> varenderD130h264dec, varenderD130postproc

Example of GPU.1 and coresponding VA codec elements, e.g. varenderD129h264dec and varenderD129postproc usage.

gst-launch-1.0 filesrc location=${VIDEO_FILE} ! parsebin ! varenderD129h264dec ! varenderD129postproc ! "video/x-raw(memory:VAMemory)" ! \
gvadetect model=${MODEL_FILE} device=GPU.1 pre-process-backend=va-surface-sharing batch_size=8 ! queue ! gvafpscounter ! fakesink
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