Reply to post: Re: Where are the benchmarks?

Famed Apple analyst chances his Arm-based Macs that Apple kit will land next year

thames

Re: Where are the benchmarks?

I've been doing a few projects in 'C' in which the tests include running benchmarks on multiple platforms. One of them is a Raspberry Pi 3.

Using a wide mix of mathematical operations on arrays, on average a Raspberry Pi 3 comes in at close to 20% of the performance of mid range desktop Intel compatible CPU running at 1.8 GHz. That's a average though, and isn't normalised according to how frequently those instructions would be encountered in a typical application.

On an individual basis they can vary between the RPi 3 actually being faster than the Intel CPU to only 10% of the speed. A lot varies on the individual CPU and whether an SIMD operation is available for that task.

A Raspberry Pi 3 is ARMv7, which only has 64 bit SIMD vectors, while the Intel CPU has 128 bit vectors (256 bit is theoretically available, but the Intel architecture is such a mess of conflicting variants that it's not practical to use it on a large scale). An ARMv8, such as is found in a Raspberry Pi 4 also has 128 bit SIMD vectors. I plan on getting my hands on a Raspberry Pi 4 to conduct more testing, but essentially it should nearly double the performance of many operations just based on having twice the SIMD width. The faster clock rate will help as well. Apple's hypothetical ARM chip, whatever that turns out to be, will I suspect be even faster than an Raspberry Pi 4 and will likely have a faster memory interface as well.

I also benchmarked an old, low end laptop dating from the Windows XP era (I put Linux on it for the test). It came in as slower than a Raspberry Pi 3.

Many of the sort of things which do very intensive numerical operations can benefit greatly from SIMD and other such hardware acceleration. There's nothing to prevent Apple from adding special processing units or instructions targetting particular use cases such as image or video editing to accelerate those to get even better performance. GPU acceleration will play a part in this as well, and some of the really intensive tasks may make use of GPU based calculations.

To make a long story short, the actual performance of a hypothetical Apple ARM PC will depend a lot on the specific use cases and how the application software was written. UI performance will be primarily GPU bound, and I don't expect Apple to use a slower GPU.

Based on my own experience, I expect that synthetic benchmarks that look at some sort of average will be almost meaningless when comparing CPUs which have a different fundamental architecture, and we would need to see application oriented benchmarks to get a real idea of how it would perform in real life.

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