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[Note: Noticed a similar question but it never received a response.]

I am using i3 on archlinux. I have setup DPMS to suspend my display after 2 minutes of inactivity (xset dpms 0 120 180). However, I've noticed that it doesn't always kick in automatically. I don't think it's a hardware issue as performing an xset dpms force works without a problem.

My settings:

$ xset q
Keyboard Control:
  auto repeat:  on    key click percent:  0    LED mask:  00000000
  XKB indicators:
    00: Caps Lock:   off    01: Num Lock:    off    02: Scroll Lock: off
    03: Compose:     off    04: Kana:        off    05: Sleep:       off
    06: Suspend:     off    07: Mute:        off    08: Misc:        off
    09: Mail:        off    10: Charging:    off    11: Shift Lock:  off
    12: Group 2:     off    13: Mouse Keys:  off
  auto repeat delay:  660    repeat rate:  25
  auto repeating keys:  00ffffffdffffbbf
                        fadfffefffedffff
                        9fffffffffffffff
                        fff7ffffffffffff
  bell percent:  50    bell pitch:  400    bell duration:  100
Pointer Control:
  acceleration:  2/1    threshold:  4
Screen Saver:
  prefer blanking:  yes    allow exposures:  yes
  timeout:  0    cycle:  600
Colors:
  default colormap:  0x22    BlackPixel:  0x0    WhitePixel:  0xffffff
Font Path:
  /usr/share/fonts/TTF/,/usr/share/fonts/OTF/,built-ins
DPMS (Energy Star):
  Standby: 0    Suspend: 120    Off: 180
  DPMS is Enabled
  Monitor is On

How can I determine what is preventing my display from suspending as per the DPMS settings?

Belmin Fernandez
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  • Some mediaplayers disable DPMS, you have to configure those to not do that. It will also help to narrow down under what circumstances it doesn't kick in (which applications are running etc.) - without that information, we are basically guessing . You can also use `xset dpms force` to test if your hardware is acting up. – dirkt Mar 31 '18 at 10:52
  • I've tried a DPMS force and that works fine. I don't have any dedicated media player although I usually have `chromium` running which is what I suspect is the culprit. However, I was hoping for a more deterministic way (e.g., a log or a command I could run in the background) to figure out which app is causing the problem. Aware of anything like that? – Belmin Fernandez Mar 31 '18 at 12:37
  • You can use an application like [xscope](https://www.x.org/releases/X11R7.5/doc/man/man1/xscope.1.html) to monitor traffic between the X server and clients like chromium, but AFAIK you can't filter for protocol extensions like DPMS (what xset uses), so you'd probably end up with a lot of data to wade through. – dirkt Mar 31 '18 at 14:26
  • @dirkt: Unless I misunderstand, `xscope` is something you need to opt-in to using *before* you run applications. In the problem cases, you already have some running applications causing havok and you are trying to find which one it is. I think `xscope` would not help with that? – jwd Jan 04 '23 at 16:54

3 Answers3

5

You can use this small program to check whether it may be a result of some user input (overly sensitive mouse?) or an app actively resetting the XScreenSaver extension idle timer:

#include <stdio.h>
#include <X11/Xlib.h>
#include <X11/extensions/scrnsaver.h>

/* Report amount of X server idle time. */
/* Build with- */
/* cc xidle.c -o xidle -lX11 -lXext -lXss */


int main(int argc, char *argv[])
{
Display *display;
int event_base, error_base;
XScreenSaverInfo info;
float seconds;

display = XOpenDisplay("");

if (XScreenSaverQueryExtension(display, &event_base, &error_base)) {
XScreenSaverQueryInfo(display, DefaultRootWindow(display), &info);

seconds = (float)info.idle/1000.0f;
printf("%f\n",seconds);
return(0);
}
else {
fprintf(stderr,"Error: XScreenSaver Extension not present\n");
return(1);
}
}
L29Ah
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3

To anyone hitting this in 2022, check .xsession_errors in your $HOME and see if something isn't preventing standby. In my case, one video in chrome was preventing the monitor turning off by DPMS

powerdevil: Enforcing inhibition from ":1.23" "/usr/bin/google-chrome-stable" with cookie 3821 and reason "Video Wake Lock"
powerdevil: Added change screen settings
powerdevil: Added interrupt session
powerdevil: Disabling DPMS due to inhibition
Solerman Kaplon
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0

To improve on @L29Ah's answer, there is a program on Github to print how long X has gone without input events: https://github.com/g0hl1n/xprintidle

So to isolate whether an X input is preventing the monitor from suspending you do:

$ xset dpms 3 3 3  # Set your monitor to turn off after 10 seconds:
$ while true; do sleep 1 && xprintidle; done

If the time keeps increasing even after 3 seconds then it's not X input that's preventing the monitor going off.

In my case it was a stray SMPlayer window that must've thought it was focused when it really wasn't. So keep closing windows until you find the one that's preventing suspend.

DBedrenko
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