Task scheduling when device is locked and not charging

asked 2013-12-28 20:09:15 +0300

axaq gravatar image

updated 2014-01-10 21:23:58 +0300

lk gravatar image

I understand power consumtion reasons to change kernel scheduling if the device is locked (black screen).

I like to run simple shell commands or scripts via ssh connection also if the device is locked. But "sleep 1" could delay for a minute or longer in locked state. Also "vmstat 1" or "top" seem to hang.

Login with ssh could take more than 2 minutes! And you shouldn't scp files during locked state without charger connected. It would take ages ...

But if I'm pinging the device from outside every second it generates regular interrupts/events and the above commands don't hang.

How to avoid this power saving feature for shell commands. Any links or hints from MER or NEMO sites?

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Did you see in dmesg output any PM suspends ?

rsainio ( 2013-12-28 20:41:00 +0300 )edit

does this have the same effect if you play music and lock the device?

AL13N ( 2013-12-28 21:10:20 +0300 )edit

@rsainio: I do see "request_suspend_state: sleep (0->3) ..." when locked (black screen) and "request_suspend_state: wakeup (3->0) ..." when lockscreen is visible (backlight on).

axaq ( 2013-12-29 03:26:27 +0300 )edit

@AL13N: Playing music and locking the device doesn't show the hanging effect. It generates enough IO events like the ping. But dmesg shows the same request_suspend_state entries.

axaq ( 2013-12-29 03:29:07 +0300 )edit

Charging the device also doesn't show the hanging effect.

axaq ( 2013-12-29 03:34:22 +0300 )edit

Correcting myself... I find that if the device has sat idle for a while (a few minutes), ssh login takes long. Also, with the screen off, anything that uses timers will take hideously long. This can be verified with

perl -e 'printf("%d\n", sleep(10));'

dmesg output available if interested.

jsiren ( 2013-12-31 20:25:46 +0300 )edit

@Milhouse i'm not entirely sure this is a duplicate, plus, you're referring to a person bug issue from someone, and considering wlan connectivity is shady by definition... it may be too early to decide this as duplicate. better remove for now.

AL13N ( 2014-01-01 23:38:53 +0300 )edit

Take a look at this thread: http://talk.maemo.org/showthread.php?t=92183

Cermit ( 2014-01-09 20:49:42 +0300 )edit