Hi, We (phone user) want to be CONNECTED for different reasons. It doesn't matter through Wifi or 3G. Switching between Wifi and 3G is VERY expensive from power consumption perspective, so switching on every screen OFF is not an option. 1 hour is too much. 1 minute is too short. We chose 15 minutes according to some power measurments for Wifi to 3G switch. If you think that for your device 5 minutes is better - you may change it. Also you may think to have this parameter as part of system properties, so it can be adjustable.
Thanks, Dmitry On Feb 5, 2:24 pm, Andrew Boie <[email protected]> wrote: > Hello, > > I have been making some observations on how WiFi behaves when the > device is put to sleep. I am seeing that even though the WiFi power > policy is set to "When Screen Turns off", the wifi driver will be > active for another 15 minutes until the device is quiescent. I have > seen two implementations of this policy so far: > > 1. On several HTC phones that I tested, and the phone I'm working on > now, the driver will reserve a wakelock in the kernel which prevents > suspend for 15 minutes. This wakelock seems to be activated when the > device goes to sleep. > > 2. On the Motorola Droid, I see that the kernel goes into suspend, but > for the first 15 minutes will frequently be woken up by SDIO > interrupts, which I imagine is due to activity on the WLAN although I > don't have visibility on the driver code. After 15 minutes these SDIO > wakeups stop and the phone stays in suspend unless woken up for some > other reason. > > During this 15 minute period, there is obviously a power penalty. For > case #1, the current used is more or less consistent, a typical result > will be around 40 mA. The Droid's mechanism seems more efficient; the > results are more variable, I observe average power consumption in the > range of 10-40 mA for any given trial, which I speculate is a function > of how often the WiFi chip is bringing the CPU out of retention. > > Does anyone have any visibility on this policy decision? Specifically: > > 1. Why do we want to keep the WiFi active like this? Is it to support > some push data scenarios? > 2. Why 15 minutes? Why not 1 minute, or 1 hour? > > Best Regards, > Andrew Boie -- unsubscribe: [email protected] website: http://groups.google.com/group/android-kernel
