About the underclocking to 768, the battery saving effect is in direct relation to the voltage specific to the cpu frequency. Coming from optimus one P500, I remember Franciscofranco explaining exemple that for that phone, any frequencies under 480 mhz were at the same voltage so it was no use to put the minimum frequency lower than that as it would basically be the same drain on the battery and more sluggish performances. On the other hand, my transformer prime goes all the way from 102 mhz up to 1.6 ghz in performance mode, though it mainly stays around 400 mhz minimum. For our phone, I put my minimum at 245 mhz and using Cooltool to monitor in real time my frequencies when the phone is only playing background music exemple it goes naturaly down to that frequency and as soon as I touch the screen there is a cpu usage spike and it rev up the frequency, to where I put my max at about 1.4 ghz. It does not feel more sluggish because it goes really fast to 1.4 and at the same time it goes by itself at lower frequencies and so less battery used.
As far as putting my maximum to 768 mhz, to save battery I guess it would depends on the exact voltage for the frequencies used. If it's the same at 768 and at 1.024 ghz, then there is no benefits from underclocking and it make the phone more slow as well. I do not know how to verify the voltage by frequencies for our kernels. Should be easy to find out.
Monitoring conservative governor versus lionheart, I find that lionheart governor is more reactive, going up and coming down faster so I prefer it to conservative even for battery savings. It is quicker to get down to my minimum 245mhz and so is the best of both worlds, fast cpu when I need it and also able to just cycle slow when idling or no touchscreen used. Cooltool on the market is really useful to get your own opinion on real life usage of governors. On our phone there is also this classic cpu spike to about 90%-100% when touching the screen but it was and endless debate on that other phone on fluidity and performance of scrolling versus battery saving. Maybe it is an android thing.
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