High CPU usage - slow/lag/skip problem

[Zurd]

Hi, me again, I'm bumping this. I realized I have a big post but I wanted
to put as much information as possible. All I want to know is how to
minimize the xrandr calls so that there's less EDID information in
Xorg.0.log.

My system is not slow yet but it should happen soon. My Xorg log is at 23M
in just 6h12m. I don't think this is normal.


On Sun, Aug 7, 2016 at 10:54 PM, Zurd <zurd33 at gmail.com> wrote:

> Hi all! I have a problem where Xorg is taking around 30% CPU usage and it
> create a slow/lag problem for a fraction of a second about every second.
> There's no crash but it's quite annoying. Sometimes a click is not
> registered.
>
> It can happen 5 minutes after I boot or after 5 hours. I haven't been able
> to know why, it's random. It looks like the same problem as this:
> https://lists.freedesktop.org/archives/xorg/2011-September/053299.html
>
> He sums it up quite well by saying:
> "I can notice the lag in response time. Video playback also becomes
> impossibly slow at this point."
>
> I started a thread on the linux mint forums with a lot of my hardware
> information:
> https://forums.linuxmint.com/viewtopic.php?f=47&t=226421
>
> Problem started with a new clean install of Linux Mint 18 and I haven't
> been able to solve it. So I went back with Linux Mint 17.2 that I had
> before and that there was no issue but now the problem is also there. I now
> have a good theory on why I have a high cpu usage of Xorg and it's because
> of my ultra widescreen monitor. When I installed Linux Mint 17.2, I had a
> regular widescreen monitor and Xorg was configured with it. Then I switched
> to my new ultra widescreen and everything was well. Until I decided to
> completely format and install the new Linux Mint 18.
>
> My monitor is an LG 29UM58-P, resolution is 2560x1080.
>
> So now I'm wondering if the problem is about EDID:
> https://wiki.ubuntu.com/X/Troubleshooting/HighCPU
> "An example we saw is where a daemon process does polling on X calls, such
> as to watch for if a monitor is present. These xrandr calls can be
> expensive because they do a probe and analysis of the monitor's firmware.
> So as a result the daemon drives X's CPU utilization through the roof (and
> causes a bunch of EDID stuff to fill up the Xorg.0.log). The solution in
> these cases is to make the daemon stop doing the expensive polling so
> frequently (there are cheaper X calls they can use)."
>
> This whole paragraph on EDID/polling/xrandr is quite interesting but
> there's no information on how to troubleshoot or solve that problem which
> is why I'm posting here. Anyone can shed some lights?
>
> I have a feeling it's about EDID because in my log file
> /var/log/Xorg.0.log, I see a bunch of
> [   434.373] (--) NVIDIA(GPU-0): LG Electronics LG ULTRAWIDE (DFP-1):
> connected
> [   434.373] (--) NVIDIA(GPU-0): LG Electronics LG ULTRAWIDE (DFP-1):
> Internal TMDS
> [   434.373] (--) NVIDIA(GPU-0): LG Electronics LG ULTRAWIDE (DFP-1):
> 340.0 MHz maximum pixel clock
> [   434.373] (--) NVIDIA(GPU-0):
> [   434.907] (--) NVIDIA(GPU-0): LG Electronics LG ULTRAWIDE (DFP-1):
> connected
> [   434.907] (--) NVIDIA(GPU-0): LG Electronics LG ULTRAWIDE (DFP-1):
> Internal TMDS
> [   434.907] (--) NVIDIA(GPU-0): LG Electronics LG ULTRAWIDE (DFP-1):
> 340.0 MHz maximum pixel clock
> [   434.907] (--) NVIDIA(GPU-0):
> [   434.940] (--) NVIDIA(GPU-0): LG Electronics LG ULTRAWIDE (DFP-1):
> connected
> [   434.940] (--) NVIDIA(GPU-0): LG Electronics LG ULTRAWIDE (DFP-1):
> Internal TMDS
> [   434.940] (--) NVIDIA(GPU-0): LG Electronics LG ULTRAWIDE (DFP-1):
> 340.0 MHz maximum pixel clock
> [   434.940] (--) NVIDIA(GPU-0):
> [   435.474] (--) NVIDIA(GPU-0): LG Electronics LG ULTRAWIDE (DFP-1):
> connected
> [   435.474] (--) NVIDIA(GPU-0): LG Electronics LG ULTRAWIDE (DFP-1):
> Internal TMDS
> [   435.474] (--) NVIDIA(GPU-0): LG Electronics LG ULTRAWIDE (DFP-1):
> 340.0 MHz maximum pixel clock
> [   435.474] (--) NVIDIA(GPU-0):
>
> If you look at the timestamp, it happens very very often and it keeps
> filling up the log file. After 23 minutes of uptime, the log file
> Xorg.0.log is already at 1.5M.
>
> Note that I'm using the latest nvidia driver and that this problem doesn't
> happen with nouveau. If I log out and back in again, the problem goes away
> but will come back.
>
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