[G2 Android Development] crnkoj:
Nice discussing with you indeed and im all for new infos, sadly due to my work and study time constraints i never get the time to start my own projects... First off, the latest mahdi was bugged, so i reverted to the 6/25 one that worked well and have been testing your kernel for a day now, it seems to work good, so my apoligies for the first report.

Anyhow in regards to the 1/2 core idle thing: i wasnt aware of the fact it turns only one core on if the screen is off, i will try the gps tracking in the near future (worst summer weather ever here right now...) and see how it drains/uses the battery and cores.

About the comparison to the moto g, the cpu it runs is a quad a7 which is approximately 50% slower per clock than the krait 400 in the g2 and per core it has a max freq of 1.2 whilst the g2 has 2.2 (which is all clear to us), but extrapolating this and the experience you had (hotplugging 1 or even 2 cores) with the moto g, it seems like it needed approximately as much burst computing power as one krait 400 core could deliver with something like 1.9-2.2ghz, hence it would seem that scrolling should be smooth even only with one krait 400 core at submaximal or maximal speeds and there would be no need for hotplugging a second core (naturally if it would have to use max speeds it ?probably? would use more power than 2 cores at lets say 1.2-1.5ghz - as the voltage jump from ~1.4ghz to 2.2ghz on the snap 800 is around 200mV - 825mV to 1025mV on my PVS 3 bin) just for simple browsing/reading text/tapatalk use/listening to music. One more thing to take into account here is that the snap 800 has support with a dedicated audio coprocessor (similar to what the motoX SoC has) as well as a rather strong GPU which (to my confusion - or did i understand that wrong) mostly runs at 320mhz even in idle or even if it runs at 200mhz its fast enough to support fluid scrolling without the need to task the CPU part of the SoC much.

Now dont get me wrong, i fully understand your point of view about the 2 core idle online. Im just a bit sceptical that qualcomm and all the other vendors who use their SoC would prefer a method of hotplugging that takes up more power than what would be optimal. I havent seen any research into the power usage of these SoC's at different speeds on variable numbers on cores, although its kind of aknowledged taht two cores at lower speeds should use less power than one at higher/max speed, much less any evidence that hotplugging a new core takes up more power than the fact that the core is the rest of the time offline saves.

So to sum up my mini-essay. I doubt that the hotplugging uses more power than the offline core saves, as compared to two permanent online cores, especially with such strong cores as the krait 400 that the snap 800 has combined with dedicated gpu/audio that can offload the main CPUs. In the end if you get the time you might try to modify it so that only one core runs and that the second core hotplug is triggered only at 90% usage at 90% of the first cores frequency (eg if the first core has 90% load at ~1.97ghz frequency). I do not know how this will effect fluency/smoothness, as i never before had the chance to try this, but it might be a viable option to test.

About the gfx core speeds, i read that you have multiple governors for it, but i failed to see speeds lower than 320mhz even in idle - and i think that there is very much power to be saved. In regards to the dedicated audio coprocessor, there is somewhere on xda a proof of concept for that, but im not sure the developer revealed how he did it - due to being afraid that things might get damaged if people experimented too much with it. If i find the post ill edit here and post the link.

Keep going :D

edit: k found it rather fast: http://www.xda-developers.com/andro...-mode-proof-of-concept-demoed-on-the-nexus-5/ possibly this might allow for lower power usage even when just listening to music with screen off or even other things in screen off mode.