[alsa-devel] [REANNOUNCE] Audio Mini Summit 2015, 8th October, Dublin

[Mark Brown]

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-alsa.html

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.
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