Some words about GCC compiler options:
I use ' Linpack' (http://elinux.org/RPi_Performance) for the PI2. And
gcc 4.9.2.
Case 1:
Default gcc option
Code:
--------------------
cc -O2 -march=armv7-a -mfloat-abi=hard -mfpu=vfpv3-d16 -o linpack linpack.c
-lm
linpack = 123279.473 kflops
--------------------
Tuned gcc options
Case 2:
Code:
--------------------
cc -O3 -march=native mtune=native -mfloat-abi=hard -o linpack linpack.c -lm
linpack = 128987.632
--------------------
Roughly 5% difference to Case 1!
Case 3:
Code:
--------------------
cc -O3 -mcpu=cortex-a7 -mfpu=neon-vfpv4 -mfloat-abi=hard
-funsafe-math-optimizations -o linpack linpack.c -lm
linpack = 159337.319 kflops
--------------------
Roughly 30% difference to Case 1!
As you can see gcc options can make a huge difference.
::: ' Touch Toolbox and more' (http://soundcheck-audio.blogspot.com) :::
by soundcheck
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