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I upgraded to Ubuntu 18.04 (from 17.10) yesterday and am currently still running the Unity desktop (same problem in Gnome desktop though).

My problem: I now have a power demand that is about 100% higher than before (around 15W vs. 8W before) without any apparent reason.

As I'm working from my laptop this means that I only get about half the battery life and since the CPU is also heating up quicker my fan is running constantly. I haven't found a quick way to measure the power while plugged in but the CPU heats up just as fast which leads me to believe that the power consumption is high as well.

This is true even when there is no demanding process:

top - 20:45:39 up 13 min,  1 user,  load average: 0,15, 0,39, 0,31
Tasks: 249 total,   1 running, 187 sleeping,   0 stopped,   0 zombie
%Cpu(s):  1,3 us,  0,4 sy,  0,0 ni, 98,2 id,  0,0 wa,  0,0 hi,  0,0 si,  0,0 st
KiB Mem :  8041660 total,  4703416 free,  2359324 used,   978920 buff/cache
KiB Swap:  1358960 total,  1358960 free,        0 used.  6148152 avail Mem 
PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND                                                                                                                             
2446 patrick   20   0 9349860 735076 154968 S   4,0  9,1   2:13.05 firefox                                                                                                                            
2519 patrick   20   0 2237800 516520 109456 S   4,0  6,4   1:09.95 Web Content                                                                                                                        
1106 root      20   0  419312 107380  71488 S   1,7  1,3   0:37.79 Xorg                                                                                                                               
2004 patrick   20   0 2178352 137972  79436 S   1,3  1,7   0:21.36 compiz                                                                                                                             
3010 patrick   20   0  803416  38208  28664 S   1,0  0,5   0:00.35 gnome-terminal-                                                                                                                    
2742 patrick   20   0 1987608 274076 102996 S   0,7  3,4   0:20.37 Web Content                                                                                                                        
2794 patrick   20   0 1882076 318820 126164 S   0,7  4,0   1:16.83 Web Content                                                                                                                        
3028 patrick   20   0   44312   4024   3396 R   0,7  0,1   0:00.11 top                                                                                                                                
1141 root     -51   0       0      0      0 S   0,3  0,0   0:03.65 irq/132-nvidia                                                                                                                     
2063 patrick   20   0   36668  12408   5928 S   0,3  0,2   0:01.14 python3                                                                                                                            
1 root      20   0  225448   9396   6840 S   0,0  0,1   0:02.16 systemd        

Prior to the upgrade I was also running tlp which extended my battery time quite a lot. After the upgrade tlp still seems to be running without any problem (click here for tlp-stat output: http://remmels.org/tlp-stat-output.txt).

Any idea why the power demand went up this much?

It's driving me crazy that I can't figure out where the problem is. At the current state this makes my laptop (1300€, 5 months old) basically useless as I rely on battery power even for work.

Please help me :)

Thanks, Patrick

My machine:

Ideapad 720s-14IKB (https://www3.lenovo.com/us/en/laptops/ideapad/ideapad-700-series/Ideapad-720S-14/p/88IP70S0833)

i7-8550U

8GB DDR4

512GB NVMe SSD

GeForce MX150 (GPU switched to Intel (Power Saving Mode))

Running Ubuntu 18.04 with Unity desktop

  • There were some kernel changes that had a dramatic effect on idle power consumption for big server systems with on the order of 100 CPUs. Not so much, but still measurable, for smaller systems. A long shot, but worth a try on your computer. Try kernel 4.17-rc7. Oh, and try enabling your watchdog. – Doug Smythies Jun 2 '18 at 14:11
  • Thanks for the advice. I played around a bit and at least found the location (if not the reason) for the problem: Apparently the NVIDIA driver or anything that gets installed along the way makes a problem in 18.04. After installing this driver (instead of Nouveau driver) the power demand is basically doubled, no matter if switched to performance (MX150) or power saving (Intel 620 GPU). Even after switching back to Nouveau and removing everything from NVIDIA, the problem still persists. That leads me to believe that something else was installed alongside and is causing the problem. – Patrick Jun 8 '18 at 9:17
  • This is not a solution suggestion, but, just in case if you want to measure the current power consumption, here is a small script that will put an indicator in the Unity's task bar: askubuntu.com/a/1024771/566421 – pa4080 Jul 11 '18 at 15:47
0

Problem: prime-select intel is not powering off the nvidia card

Workaround: Fast Switch Prime-Ubuntu-18.04

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