Compiz causing high CPU load in Ubuntu 18.04 Bionic

[roots]

Hi,

I'm running Ubuntu 18.04 Bionic daily with proposed updates enabled. I am using gnome-flashback (gnome-panel) with Compiz and am getting high CPU loads attributed to Compiz. That is, Compiz is permanently hovering at around 10..50% and peaking at 800%. Considering my H/W specs below, this appears a bit "unusual". CPU usage is peaking when resizing desktop windows and scrolling pages in Firefox.

Important hint: When I check GPU usage with intel-gpu-tools, the GPU seems to be idling, with GPU frequency at minimum and GPU usage staying at 0% even when doing wild window resizes. On my Ubuntu 16.04 (see below), this will get me up to 20..30% GPU usage.

H/W:

CPU: Core i7-7700k @ 5GHz
GPU: Using Intel IGP (HD630)
RAM: 16GB DDR4
SSD: Intel Optane

S/W:

$ cat /proc/version
Linux version 4.15.0-11-generic (buildd@lgw01-amd64-016) (gcc version 7.3.0 (Ubuntu 7.3.0-5ubuntu1)) #12-Ubuntu SMP Fri Feb 23 18:39:58 UTC 2018

$ lspci -nnk | grep -iA2 vga
00:02.0 VGA compatible controller [0300]: Intel Corporation HD Graphics 630 [8086:5912] (rev 04)
 Subsystem: Gigabyte Technology Co., Ltd HD Graphics 630 [1458:d000]
 Kernel driver in use: i915

$ modinfo i915
srcversion: 4963AD5BD78D754BBD09EAF
name: i915
vermagic: 4.15.0-11-generic SMP mod_unload
signat: PKCS#7

$ dpkg -l | grep compiz
ii compiz 1:0.9.13.1+18.04.20180302-0ubuntu1
$ dpkg -l | grep xserver-xorg-video-intel
ii xserver-xorg-video-intel 2:2.99.917+git20171229-1 amd64
$ dpkg -l | grep xorg
ii xorg 1:7.7+19ubuntu5 amd64
$dpkg -l | grep mesa
ii libegl1-mesa:amd64 18.0.0~rc4-1ubuntu3

I also tried todays latest GFX drivers from the oibaf ppa, but that did not make any difference.
On another Ubuntu 16.04 install, I'm running compiz 1:0.9.12.3+16.04.20171116-0ubuntu1 without any issues.

Cheers,
r.

[roots (roots)]

Ok, I did some digging further and figured, that obviously the GPU is not being used at all when OpenGL apps are run.
I launchend glmark2 and checked intel_gpu_top and top: While the GPU usage remained at 0%, glmark2 sent the CPU usage to >200%.

So maybe this is not a Compiz bug then, however - any pointers appreciated!

r.

[roots (roots)]

Status changed to invalid, as I was obviously not using GPU rendering after applying some updates from Proposed. Did a clean 18.04 reinstall and problem does not occur anymore.