Dan Williams <[email protected]> writes: > 1) Passive scanning on any recent wifi chipset does not consume > significantly more power than normal TX operation
OK, so I made some more power comparisons between ifupdown and NetworkManager. Theories are good but nothing replaces actual experience. With ifupdown, my laptop draws about 9.3W +- 0.1W, as reported by powertop querying ACPI. Switching the wireless interface to connected, disconnected, rf_kill-ed, rmmod-ed, has almost no measurable effect on this. With NetworkManager, my laptop draws about 10W when I am connected, and about 10.2W (!) when I disable wireless. I assume this is all because of background scanning, about which I could not care less. I am afraid I will have to give up NetworkManager for the moment. Maybe I will give it another try the next time I will upgrade my distribution. And I will come prepared this time :-) > 2) If the user is not actively using the wifi connection, there is no > reason to keep the wifi chip powered on That's it. Well, that does not solve my almost +1W power problem when I _am_ actively using it. And I unfortunately do not see this rf_kill happening yet when I am not connected. > Keep clear, delineated lines between your > components and your system will be simpler and more reliable. > [...] > Because NetworkManager is not a power saving daemon. As explained > above, power saving needs to be system wide and NetworkManager should > not be talking to a bunch of other components to get power state. If we > did, we'd have to write new code each time somebody wrote a new power > daemon. Instead, NetworkManager provides a rich D-Bus interface that > things like power daemons can talk to to get network state and figure > out what exactly they need to do to implement their power saving policy. This sound like great architectural design, but: - as said above, this does not seem to happen yet - background scanning is a feature totally useless to me in any situation. The only time I need a scan is before connecting, period. - With my specific hardware, background scanning is a killer. Once I get rid of background scanning I do not even need this super-duper power manager of the future to control my wireless card: my power issues are already solved. Is background scanning really rooted deep down in the design of NetworkManager? If yes, I am afraid I will have to give it up and never come back to it. Too bad I have to go to the command line again. >> > But at the end of the day, if you want to save power, you'll want to >> > turn off the wifi chipset when the user isn't going to use it. Well, not necessarily. With my hardware, turning off background scanning seems enough to save power. >> >> I prefer to loose 2 or 3 seconds to get the first list of available >> >> APs than loose battery life during the X minutes (or hours) scanning >> >> and keeping the wireless card on. Definitely yes. _______________________________________________ NetworkManager-list mailing list [email protected] http://mail.gnome.org/mailman/listinfo/networkmanager-list
