Below are two benchmarks that explore maximum floating point performance. loopm6 is double precision floating point and loopm6fp is parallell single-precision. They are manually unrolled multiply-add loops.
I used to reach 2.8 and 11 GFlops on these. Now I only get 2 and 6. If you explore the inner loop with gcc -O2 -S you can see that it seems to use few registers. If you run them, there is a parameter expected. I use 30000 - 50000. gcc 4.9.2-3 on 64-bit. I use gcc -O2.
loopm6.c
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loopm6fp.c
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timers.h
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