raspi -- hardfloat-2

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Raspbian Benchmarking – armel vs armhf


Performance Results

To try to quantify the optimisations in Raspbian I extended my benchmarking tests and ran them on the two different architectures, Debian armel and Raspbian armhf.

The tests were run on a single Raspberry Pi using two different partitions on the same USB hard disk. The same kernel was used for both sets of tests. Tests were performed multiple times until a “best” score was reached. For the GTKPerf tests both Raspbian and Debian were set to the same GTK theme. I chose not to use the raw data, but present it in an easier to understand format, armhf performance is presented relative to armel performance.

Keep in mind the golden rule of benchmarking: All benchmarks are flawed benchmarks.
Performance comparison between Debian armel and Raspbian armhf
Performance comparison between Debian armel and Raspbian armhf

The chart above shows the performance difference in various applications between Debian armel and Raspbian armhf. Performance improvement varied from 4% to 40% depending upon the application.
The performance improvements seen by non-floating point applications like Gzip and Bzip2 and were related to the ARMv6 instructions being used instead of the ARMv4 instructions. We seem to gain 4-10% in these applications.

GTKPerf showed a 19% improvement in X Windows GUI operations, which should make the Raspberry Pi more usable as a desktop. Quake 3 showed a more modest improvement, but that is because it is already limited by the GPU at 1080p resolutions.

The applications with larger performance improvements are those making heavy use of floating point maths, particularly media en/decoding, which see a huge performance increase. I also saw a 600% increase in Mpeg Layer 3 and Layer 2 encoding performance, but I didn’t include that on this chart as it made the other data difficult to read.

Users of the latest OpenSSL packages will see a ~100% performance increase over these numbers, which is related to an ASM optimisation patch applied by the Raspbian team and isn’t relevant to this test. It does demonstrate how important optimisation is though!


I believe the QtonPi wiki best sums up my experiences:

Given the preponderance of hardfp performance over its register ignorant peers, this will be useful in eking every last drop of performance out of the hardware.


Raspberry Pi Hard Float Benchmarks


As expected, the hardware floating point execution was significantly faster than the software emulation. Perhaps by a factor of 10x or better.