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This is a strange one, and I've noticed it on multiple distros, and Arch is no different. When my system is sitting idle with the screen on my CPU usage hovers around 5%, which I would consider to be perfectly normal. However, when the display goes to sleep (no screen saver, just DPMS sleep) the CPU jumps up to about 25% and stays there until I bump the mouse (or do whatever to wake the system up), and then it will drop back down to the normal 5% CPU usage.
I had always thought it had something to do with Firefox, but I had Firefox closed while I was away at work today, and yet when I come home and wake my computer up my CPU usage graph shows that it's been at a solid 25% all day long.
Anyone have any ideas what this might be, or recommend a way to hunt down exactly what process is eating my CPU cycles while the display is off?
Thanks a lot, this has been puzzling me for some time now.
EDIT: I should add that I am running KDE, and have been on the other distros as well (to the best of my recollection). After realizing this it seems like this thread may be better suited for the Applications & DE forum, but I'm not sure... it could very well be something to do with the kernel or something to do with power saving. Please move if you see fit.
Last edited by hippieben (2014-09-07 00:17:46)
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Run a script that logs the top n most cpu-intensive tasks, turn the display off, wait a bit, wake the display up.
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Run a script that logs the top n most cpu-intensive tasks, turn the display off, wait a bit, wake the display up.
Unfortunately my scripting skills are pretty lacking.
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Try
for i in $(seq 1 10); do sleep 10 && ps -eo pcpu,pid,user,args | sort -rk1 | head -6; doneEdit: It runs
ps -eo pcpu,pid,user,args | sort -rk1 | head -610 times, every 10 seconds. that one-liner prints top 5 most cpu-intensive processes. You can tweak these numbers of course.
Last edited by karol (2014-09-07 03:30:47)
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The CPU usage is not accounted for in the system monitor app. There's roughly 4% usage accounted for, yet there's a total of 29% being used.
The script doesn't seem to find anything either. High idle CPU usage kicks in maybe 3/4 of the way through, but the output doesn't seem to change from the beginning at all.
ben@arch-desktop:~$ for i in $(seq 1 20); do sleep 10 && ps -eo pcpu,pid,user,args | sort -rk1 | head -6; done
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefox
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefox
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefox
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefox
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefox
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefox
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefox
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefox
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefox
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefox
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefox
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefox
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefox
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefox
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefox
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefox
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefox
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefox
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefox
%CPU PID USER COMMAND
6.0 428 root /usr/bin/Xorg.bin -br -novtswitch -quiet :0 vt7 -nolisten tcp -auth /var/run/xauth/A:0-biq1sc
3.8 3690 ben /usr/lib/firefox/plugin-container /usr/lib/mozilla/plugins/libflashplayer.so -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 3231 plugin
2.4 4910 ben /usr/bin/systemsettings -caption System Settings --icon preferences-system
2.4 14853 ben clementine -t
1.9 3231 ben /usr/bin/firefoxAlso, the screen doesn't have to be asleep, the system just needs to sit idle for a few minutes.
Last edited by hippieben (2014-09-20 19:10:58)
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Maybe it's I/O related? Is some indexing daemon scheduled to run when the system is idle?
Since the display can still be on, you can just use htop to check this out.
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