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 decodebin 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 decodebin) 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 "... ! decodebin force-sw-decoders=true ! 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 "... ! decodebin ! gvadetect device=GPU ! ..."