14.07.2015 21:17, Mark Brown wrote:
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.htmlsaying there was a 0.4W win (I think Arun had some similar numbers).
Thanks for the link. I have no reason to doubt these measurements. Note, however, that they are of the "pulseaudio vs pulseaudio" type, and give no insight into the structure of the win. By "structure", I mean the proportion of energy wasted due to the wakeup itself, in the kernel code, and in the pulseaudio code. IOW, they, technically, don't rule out the "pulseaudio is inefficient at low latencies, and that's pulseaudio's fault" possibility. That's why (and also because, on my hardware, the win with hw:0 and aplay is smaller) I want to do some cross-comparisons of various sound servers to the raw hw:0 device. It would also be nice to be able to see directly the effect of David's work on srbchannel.