MediaEngine usage, Encode & Decode

[na-ate]

Hi !

I write to you because I discovered amdgpu_top tonight and I am hyped about it !
It fills the void left by radeontop and brings more features, more usability, and display way more info !
Thank you very much for this piece of open source software.
I've used it a bit and I intend to use it to monitor the GPU usage of my amdgpu when decoding/encoding videos.

I have a

drm version: 3.59.0

Device Name              : [AMD Radeon 780M Graphics]
PCI (domain:bus:dev.func): 0000:c1:00.0
DeviceID.RevID           : 0x15BF.0xC4
gfx_target_version       : gfx1103

GPU Type  : APU
Family    : GC 11.0.1
ASIC Name : GFX1103_R1/Phoenix1
Chip Class: GFX11

in my Framework 13.
I have the following installed:

ii  amdgpu-top                              0.10.4-1                                amd64        Tool to displays AMDGPU usage.
ii  libdrm-amdgpu1:amd64                    2.4.123-1~bpo12+1                       amd64        Userspace interface to amdgpu-specific kernel DRM services -- runtime
ii  libdrm2:amd64                           2.4.123-1~bpo12+1                       amd64        Userspace interface to kernel DRM services -- runtime

I run Debian 12.10 on my laptop

Linux framework 6.12.12+bpo-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.12.12-1~bpo12+1 (2025-02-23) x86_64 GNU/Linux

I then proceed to launch a hardware transcoding with ffmpeg:

ffmpeg -hwaccel vaapi -hwaccel_output_format vaapi -vaapi_device /dev/dri/renderD128 -i input.mkv -vf 'format=vaapi,hwupload' -c:v hevc_vaapi output.mkv

I then notice two things in qmdgpu_top:

• the MediaEngine usage is at 100% in GPUActivity but in the fdinfo section the line for ffmpeg shows only ~ 30-40%
  

• Encode and Decode engines usage stays at 0% in the JSON output

      "Total fdinfo": {
        "Compute": {
          "unit": "%",
          "value": 0
        },
        "DMA": {
          "unit": "%",
          "value": 0
        },
        "Decode": {
          "unit": "%",
          "value": 0 # stays 0 ?
        },
        "Encode": {
          "unit": "%",
          "value": 0 # stays 0 ?
        },
        "GFX": {
          "unit": "%",
          "value": 0
        },
        "GTT": {
          "unit": "MiB",
          "value": 124
        },
        "Media": {
          "unit": "%",
          "value": 36 # Only 36% here, despite the 100% of the MediaEngine
        },
        "VCN_JPEG": {
          "unit": "%",
          "value": 0
        },
        "VPE": {
          "unit": "%",
          "value": 0
        },
        "VRAM": {
          "unit": "MiB",
          "value": 1305
        }

When I go to GPU activity I see the MediaEngine to 100%

      "gpu_activity": {
        "GFX": {
          "unit": "%",
          "value": 0
        },
        "MediaEngine": {
          "unit": "%",
          "value": 100 # 100% here
        },
        "Memory": {
          "unit": "%",
          "value": null
        }
      },

Is it normal that Encode and Decode stays null even if my GPU is RDNA 3.0 ?
The readme states here that they should not show but for RDNA 4.

And I wondered why I had a difference between the VCN/Media usage in fdinfo vs the one in Activity.

Thanks for future answers, and thanks for the tool !

[Umio-Yasuno]

"MediaEngine" is the usage reported by the System Mangement Unit (SMU) in hardware, fdinfo is the usage calculated from the driver-reported usage time.
amdgpu_top calculates the media usage as the average of the video decoder/encoder and the JPEG decoder usage.
Up until RDNA 2, that calculation roughly matched the SMU reported usage.
https://github.com/Umio-Yasuno/amdgpu_top/blob/main/crates/libamdgpu_top/src/stat/fdinfo/amdgpu_fdinfo.rs#L203-L217

The readme states here that they should not show but for RDNA 4.

Sorry. It was my mistake.

[na-ate]

Great ! Thank you for the info !