Expected Behavior

Utilizing Metal on a 2019 imac5k with a Radeon Pro Vega 48

Current Behavior

All runs fine, but metal uses the Intel HD graphics internal card instead of the Vega GPU

Solution

You are using "ctx->device = MTLCreateSystemDefaultDevice();" in ggml-metal.m
You need to use "MTLCopyAllDevices" to get an array.

https://developer.apple.com/documentation/metal/gpu_devices_and_work_submission/multi-gpu_systems/finding_multiple_gpus_on_an_intel-based_mac

Environment and Context

Please provide detailed information about your computer setup. This is important in case the issue is not reproducible except for under certain specific conditions.

Mac os: 13.4.1
Chipset Model: Radeon Pro Vega 48
Type: GPU
Bus: PCIe
PCIe Lane Width: x16
VRAM (Total): 8 GB
Vendor: AMD (0x1002)
Device ID: 0x6869
Revision ID: 0x0000
EFI Driver Version: 01.01.072
Metal Support: Metal 3

Model Name: iMac
Model Identifier: iMac19,1
Processor Name: 6-Core Intel Core i5
Processor Speed: 3,7 GHz
Number of Processors: 1
Total Number of Cores: 6
L2 Cache (per Core): 256 KB
L3 Cache: 9 MB
Memory: 24 GB