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connman/lipstick stuttering and battery drain with WLAN enabled

Tracked by Jolla (In release)

asked 2019-11-01 13:44:46 +0300

mia gravatar image

updated 2019-11-02 12:28:09 +0300

Connman does something periodically (scanning WLANs?) that causes lipstick to stutter every few seconds, network I/O to stall and constant background CPU usage when WLAN is enabled. This also drains the battery very quickly, to the point where an Xperia X with no running apps and the display off won’t last even one day.

This happens whether or not the device is connected to a network, but the effect is much worse when no known networks are nearby.

Disabling WLAN makes these problems go away.

Edit: I just checked dbus-monitor and indeed it looks like connman is scanning wifi networks every 3 seconds or so, and then dumps all the info, which is very slow. This explains the above observations.

Edit 2: Setting breakpoints in connman with gdb points to connman/plugins/sailfish_wifi.c as the source of the problem. The autoscan timer appears to get registered too many times, which causes it to get triggered way too frequently. I have not tried to confirm this though.

Edit 3: Found the offender, at least for the case where there’s an active connection: https://git.sailfishos.org/mer-core/connman/blob/master/connman/plugins/sailfish_wifi.c#L2645-2648

Commenting these lines fixes the problem but I have no idea why they’re there in the first place.

Edit 4: Found what’s causing problems when not associated with a network: https://git.sailfishos.org/mer-core/connman/blob/master/connman/plugins/sailfish_wifi.c#L2859-2868

IMO this is completely unnecessary.

tl;dr connman has never been tested in densely populated areas with lots of wifi networks, and scans way too frequently, which drains the battery and makes the system less responsive

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my xperia x has much better battery life with and my Wlan stays always on. But it's still way less compared with android.

danfin ( 2019-11-01 17:59:17 +0300 )edit

The WLAN activity also interferes with BT music streaming, causing the music to stutter regularly. For this reason I have WLAN turned off at all times unless I actually need it.

Your explanation sounds like the root cause of this issue as well.

I have not had to to verify whether the problem still exists in yet (I have an X).

DrDweeb ( 2019-11-02 05:44:16 +0300 )edit

Just commenting to say that's a very well researched report.

aerique ( 2019-11-08 13:21:56 +0300 )edit

1 Answer

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answered 2019-11-02 13:05:17 +0300

spiiroin gravatar image

FYI: I created an internal ticket about this.

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Asked: 2019-11-01 13:44:46 +0300

Seen: 350 times

Last updated: Nov 02 '19