On Tue, Jul 14, 2015 at 09:04:30PM +0500, Alexander E. Patrakov wrote:
I would like to see some direct measurements related to recent power-saving proposals, including the "disable rewinds" flag. Myself, I can redo battery-life measurements on Intel-based laptops that my colleagues have, and maybe compare dmix, PulseAudio and CRAS in terms of power consumption.
The numbers I seem to remember seeing at the time were these IIRC:
http://linux-tipps.blogspot.co.uk/2011/04/power-performance-of-pulseaudio-al...
saying there was a 0.4W win (I think Arun had some similar numbers).
Ideally, I would like to reevaluate the design decisions (namely, the need to keep the system responsive to new streams while keeping the average wakeup rate as low as possible, IMHO even to the point of "absurdly low") that led to the need to support rewinds (and the associated complexity) in the first place. Reminder: on my Sony VAIO VPC-Z23A4R laptop and hw:0 device, in an unrealistic test with the screen turned off, wi-fi turned off, and the SSDs put to sleep, going from 200 to 1 wakeup per second saved only 935 seconds of battery life out of 25742.
I'm not sure how many embedded people would be willing to provide numbers but it definitely makes a substantial difference there if you can keep the CPUs powered down.