WiFi continues to scan in the background, affecting performance
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Matt Ranostay March 20, 2019 at 12:22 AM
Connman 1.36 should improve this well enough. But likely anything more is related to the RPI3 hardware + kernel drivers.
Edi Feschiyan February 26, 2019 at 4:38 PMEdited
I have used vaping python utility for monitor and graph latency against hosts with 10 requests per second.
I have used the older Raspberry Pi 3B
The attached text files contain the iw event listener logging output during scanning
Flooding both interfaces with ~500 pings/sec shows no noticeable increase in latency
- logging during flooding the interfaces
- logging during normal operation
The increase in the latency is caused by regular 5 minute intervals per interface. No other scans are observed unless invoked manually.
The whole time the RPI3 was on the settings->wifi screen.
During the ping flood - the result of fping is the following
During normal operation - the pings do not spike above 300 msec while scanning and there are no packets lost.
Edi Feschiyan February 26, 2019 at 7:06 AM
, i have pasted results both from the onboard wifi and the external adapter in my last comment.
I have a spare rpi3 in the office, I was testing only on 3B+, I'll test this today on the old 3B
Matt Ranostay February 26, 2019 at 2:20 AM
To confirm this is with the onboard Wi-FI, or external adapter?
Dennis Field February 25, 2019 at 4:09 PM
Yeah. I was paranoid that I didn't actually flash an updated version, so I even double checked by reverting the commit from 20127 and checking to see that the version had indeed changed (it did). I'm running 1.36 now.
This affects two different Pi 3B boards I've tested, but not the 3B+. Only once settings has been opened. As soon as I kill the afm-api-network-manager@0 service it goes back to normal
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Matt RanostayReporter
Dennis FieldComponents
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Major
When I open Settings, connect to a WiFi network, and then leave the WiFi network list or switch away from Settings, the network list is still scanned in the background every 5-10 seconds, which makes wifi performance suffer. e.g. SSH connectivity for browsing logs, pinging, doing POI search.
The network list should not be scanned continuously when it is not visible on screen. This behavior matches what users expect from smartphones, tablets, computers, etc.
I tried a few things that I thought might make it stop (including editing the wifi app to "unsubscribe" from API events) but nothing I did changed the situation. Once settings has been opened, the network list gets scanned every so often and anything that is sensitive to packet latency like typing or scrolling becomes unusable
I can sometimes kill the Settings app entirely and that will remedy the situation after the next network scan has no place to put its list.
Couldn't find any code that corresponded to an "interval" to give to connman to continuously scan, nor could I find a "stop" command.