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Changes to Linux "Interactive"-Governor

Question asked by Marc-Oliver Westerburg on Mar 8, 2016
Latest reply on Mar 9, 2016 by Qiang Li - Mpu Se
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Hi all,

 

I just noticed that Freescale/NXP seems to be using a completely re-written custom "interactive" CPU-Governor in the Yocto BSPs based on the 3.10.17 kernel (drivers/cpufreq/cpufreq_interactive.c) with a copyfright from 2010 by Google and 2012/2013 by Freescale, instead of a completely different one in Yocto BSPs based on 3.10.53 and 3.14.x kernels, with a copyright only by Google from 2010 (apparanetly without any modifications by Freescale).

 

Our own Yocto BSPs for our own i.MX5x- and i.MX6x-based systems are still based on the 3.10.17 kernel and we noticed, that even with Freescale/NXP's demo-images on Sabre boards the systems behave differently when scaling the CPU frequency up and down depending on whether we run 3.10.17- oder 3.10.53-based Yocto demo-images.

 

What was the reason for the custom "interactive" governor in the 3.10.17-based BSPs and why are entirely different unmodified versions of the "interactive" governor used again in all newer BSPs? Would it be possible (or even better) to port the "interactive" governor of the the newer kernels back to 3.10.17?

 

Kind regards,

Marc

 

 

Edit: I modified my questions because at first I thought the "interactive" governor used in the 3.10.53+ BSPs to come from mainline linux, but it seems that the mainline linux-kernel doesn't come with an "interactive" governor. This seems to be coming from Google's Android instead.

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