ggml_vulkan_device_groups: Probe Vulkan device groups (NVLink / multi-GPU peer access)

In ggmlR: 'GGML' Tensor Operations for Machine Learning

Probe Vulkan device groups (NVLink / multi-GPU peer access)

Description

Enumerates Vulkan device groups (VK_KHR_device_group, also known as Linked Device Adapter / LDA) and probes whether the driver reports direct peer memory access between the physical GPUs in each group.

Usage

ggml_vulkan_device_groups()

Details

A device group with more than one device and peer copy/generic memory features is the prerequisite for true GPU-to-GPU transfers routed over NVLink (or PCIe peer-to-peer) through a single device-group logical device — as opposed to sharing memory as an opaque fd between independent devices, which the driver may route through host memory.

This is a diagnostic only: it does not create any long-lived device group. On a machine with a single GPU it reports zero multi-device groups. Device groups for compute are effectively an NVIDIA feature; AMD/RADV typically reports only single-device groups.

Value

A named list with n_groups (integer, number of device groups reported by the driver) and report (character, a human-readable per-group diagnostic including peer memory features). Use cat() on report to read it.

Examples

if (ggml_vulkan_available()) {
  g <- ggml_vulkan_device_groups()
  cat(g$report)
}

ggmlR documentation built on July 14, 2026, 1:08 a.m.