meta-sunxi/README.md
2014-02-03 18:37:56 +01:00

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meta-sunxi
==============
Official sunxi OpenEmbedded layer for Allwinner-based boards.
This layer depends on the additional layer:
meta-openembedded: git://git.openembedded.org/meta-openembedded
Tested with core-image-base.
Maintainers:
* Nicolas Aguirre <aguirre.nicolas@gmail.com>
* Enrico Butera <ebutera@users.berlios.de>
* Sergey Lapin <slapin@ossfans.org>
Performance
===========
The default machine settings are meant to be the lowest common denominator, maximizing generality.
Significantly better performance (2x-3x) can be achieved with the following settings:
**_Allwinner A20_**
For Allwinner A20 (Cubieboard2/CubieTruck), the following tuning options are recommended:
_Enable hardfloat, thumb2 and neon capabilities_
DEFAULTTUNE = "cortexa7hf-neon-vfpv4"
This tuning profile takes advantage of the Allwinner A20 hardfloat, neon and vfpv4 capabilities.
_Change CPU governor to ondemand, and tune settings_
echo ondemand > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
echo 336000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq
echo 912000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
#More aggressive
#echo 1008000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
echo 40 > /sys/devices/system/cpu/cpufreq/ondemand/up_threshold
echo 200000 > /sys/devices/system/cpu/cpufreq/ondemand/sampling_rate
This code changes the default CPU governor from _fantasy_ to _ondemand_, and tunes its settings, as recommended at http://linux-sunxi.org/Cpufreq
For additional discussion, see https://github.com/linux-sunxi/meta-sunxi/issues/25