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trilader

Member

Registered: 2020-12-23

Posts: 1

Poor graphics performance/high CPU usage on Thinkpad T14 (Intel, 4k)

I recently bought myself a Thinkpad T14 with Intel CPU and 4k Display it has a Intel UHD 620 GPU. It also has a Nvidia GPU which I'm not using (nvidia and nouveau are blacklisted).

I'm getting really poor performance/very high CPU utilization when either viewing video with mpv (fullscreen, with VAPPI enabled and dropping frames) or using Jitsi Meet in Chromium to the point of it being unusable (really high CPU usage >400% according to htop) and video stuttering and sound glitches also when watching YouTube videos.

I'm running KDE at 200% scaling.
intel-media-driver is installed. xf86-video-intel is not.
glxinfo says the Intel GPU hardware acelleration is available.

As far as I can tell it's not a hardware issue as I don't have the issue when booting from a Ubuntu 20.10 live USB or when running Windows.

intel_gpu_top shows "Render/3D/0" is at 100% in those cases.

I've also tried reducing the screen resolution to 1080p (and let the hardware scale it up) so the GPU has pixels to fill. mpv with vaapi works in that case. Jitsi Meet still uses too much CPU.

I'm not sure what to try to resolve this or where to start looking so I'm happy to get some hints/solutions.

twobooks

Member

From: rainforest

Registered: 2020-06-23

Posts: 46

Re: Poor graphics performance/high CPU usage on Thinkpad T14 (Intel, 4k)

this book equipped with Nvidia GPU is right for your 4K display,
I don't understand why you blacklist it.

liewkj

Member

Registered: 2019-07-08

Posts: 210

Re: Poor graphics performance/high CPU usage on Thinkpad T14 (Intel, 4k)

intel_gpu_top shows "Render/3D/0" is at 100% in those cases.

You should see activity in "Video/0" and "VideoEnhance/0" in intel_gpu_top. "Render/3D/0" simply show that the video was rendered using the GPU, but decoding is still using the CPU. Decoding 1080p60 or 4K is not going to do well on mobile CPUs without hardware acceleration. The workload of displaying video consists of decode and then render. For mobile CPUs, it is prefer to have hardware acceleration on both.

If the KDE is using Wayland compositor, then the official Chromium does not support VA-API to use the GPU for video decoding. It still support using GPU for video rendering though. This is where you saw 100% at "Render/3D/0" from intel_gpu_top.

@twobooks
Unless the software support NVIDIA propriety NVENC/NVDEC APIs for video applications (and Chromium does not), Intel media block acceleration works much better than NVIDIA GPUs through VA-API.

Last edited by liewkj (2020-12-25 22:18:12)

twobooks

Member

From: rainforest

Registered: 2020-06-23

Posts: 46

Re: Poor graphics performance/high CPU usage on Thinkpad T14 (Intel, 4k)

if wayland doesn't support Nvidia GPU, I'd go with X11 and let the $200 Nvidia GPU run.