Since the new Raspbian distribution has hardware accelerated floating point operations, I wanted to test how fast the Raspberry Pi can run. But what to use for a benchmark? Well, LINPACK is the historical choice for evaluating floating point performance. Sure, the Pi doesn’t come with a FORTRAN compiler, but there is a C version of the benchmark that I got to compile with a few minor changes.

Using the Raspbian Wheezy (2012-09-18) image, here are the results from linpack:

```
Rolled Double Precision Linpack
norm. resid resid machep x[0]-1 x[n-1]-1
1.7 7.41628980e-14 2.22044605e-16 -1.49880108e-14 -1.89848137e-14
times are reported for matrices of order 100
dgefa dgesl total kflops unit ratio
times for array with leading dimension of 201
0.02 0.00 0.02 34333 0.06 0.36
0.01 0.00 0.01 68667 0.03 0.18
0.01 0.00 0.01 68667 0.03 0.18
0.02 0.00 0.02 40655 0.05 0.30
times for array with leading dimension of 200
0.02 0.00 0.02 34333 0.06 0.36
0.02 0.00 0.02 34333 0.06 0.36
0.01 0.00 0.01 68667 0.03 0.18
0.02 0.00 0.02 42256 0.05 0.29
Rolled Double Precision 40655 Kflops ; 1000 Reps
```

So that works out to be 41 MFLOPS. Not bad for a 700 MHz processor. But what if we do enable overclocking with the following command:

```
sudo raspi-config
```

then, under the overclocking section, choose the Turbo option:

```
Turbo 1000MHz ARM, 500MHz core, 500MHz SDRAM, 6 overvolt
```

The turbo mode runs at 1000 MHz and gives the following results:

```
Rolled Double Precision Linpack
norm. resid resid machep x[0]-1 x[n-1]-1
1.7 7.41628980e-14 2.22044605e-16 -1.49880108e-14 -1.89848137e-14
times are reported for matrices of order 100
dgefa dgesl total kflops unit ratio
times for array with leading dimension of 201
0.01 0.00 0.01 68667 0.03 0.18
0.01 0.00 0.01 68667 0.03 0.18
0.01 0.00 0.01 68667 0.03 0.18
0.01 0.00 0.01 62709 0.03 0.20
times for array with leading dimension of 200
0.01 0.00 0.01 68667 0.03 0.18
0.01 0.00 0.01 68667 0.03 0.18
0.01 0.00 0.01 68667 0.03 0.18
0.01 0.00 0.01 65149 0.03 0.19
Rolled Double Precision 62709 Kflops ; 1000 Reps
```

The overclocking improves the performance to 63 MFLOPS. To provide some comparison values, here are the comparison numbers from the Linpack Benchmark Report:

Year | Computer | MFLOPS |
---|---|---|

1988 | CRAY Y-MP | 74 |

2012 |
Raspberry Pi (Turbo mode) |
63 |

1987 | ETA 10-E | 52 |

1986 | NEC SX-2 | 46 |

1985 | NEC SX-2 | 46 |

2012 |
Raspberry Pi (Stock) |
41 |

1984 | CRAY X-MP | 21 |

1983 | CRAY 1 | 12 |

1979 | CRAY 1 | 3.4 |

So, the Raspberry Pi that I bought for $35 is the number-crunching equivalent of three Cray X-MP supercomputers. Not bad.