Update: (title changed) It seems that enabling the GPU causes the i7 CPU to throttle down to around 200MHz. The CPU is not hot (65 deg C) so I am not sure why this is happening. This very low frequency in turn causes high CPU load (because it can not process the instructions quick enough, they pile up). Any suggesstions would be appreciated.
I have just purchased a new ThinkPad E590 (i7 8565-U with UHD 620, AMD RX 550X GPU). I have installed Ubuntu 19.04 and everything works very well, except that when I start an application with the AMD GPU enabled, the CPU usage goes up to around 400% (4 cores X 100%). Running the same application from the Intel graphics results in CPU usage around 150%.
I am using the open source amdgpu driver built in to the kernel. Benchmarks like unigine-heaven give me (FPS) results which are very similar to what I get on windows, but the massive CPU load causes the animations to stutter. This is also true of Steam games (Dungeons 3, Cities: Skylines), which perform so bad, that they are unplayable. I do not have this problem with my old XPS15 (Ubuntu 19.04 / i7 4712HQ / Nvidia GT750M) which runs the same games very well, so I assume that the ThinkPad with much faster CPU/GPU should have no problems.
Does anyone have any suggestions on solving this? Any help would be appreciated.
My system details:
Kernel: 5.0.0-15-generic x86_64 bits: 64 compiler: gcc v: 8.3.0
Desktop: Gnome 3.32.0
Distro: Ubuntu 19.04 (Disco Dingo)
Machine: Type: Laptop
System: LENOVO product: 20NBCTO1WW v: ThinkPad E590 serial: XXX
Mobo: LENOVO model: 20NBCTO1WW v: SDK0J40709 WIN serial: XXX
UEFI: LENOVO v: R0YET31W (1.14 )
Topology: Quad Core
model: Intel Core i7-8565U
type: MT MCP
arch: Kaby Lake rev: B L2 cache: 8192 KiB
Device-1: Intel UHD Graphics 620
bus ID: 00:02.0
Device-2: AMD Lexa PRO [Radeon 540/540X/550/550X / RX 540X/550/550X]
bus ID: 03:00.0
Display: x11 server: X.Org 1.20.4 driver: amdgpu resolution: 1920x1080~60Hz
renderer: Mesa DRI Intel HD Graphics (Whiskey Lake 3x8 GT2)
v: 4.5 Mesa 19.0.2 direct render: Yes
Sensors: System Temperatures: cpu: 52.0 C mobo: N/A gpu: amdgpu temp: 44 C
Fan Speeds (RPM): cpu: 0
Compilers: gcc: 8.3.0
Shell: bash v: 5.0.3 inxi: 3.0.33