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Is Intel within ARM’s reach? Pedestrian Detection shows the way

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Re: Is Intel within ARM’s reach? Pedestrian Detection shows the way

#31

Post by acqq »

ranjithparakkal wrote: post #23
Scaevolus wrote: post #12

Earlier quoted context omitted.

People always focus on the instruction set -- "ARM's fixed length instructions are easy to decode, so it will win in the long run" -- ignoring how decoding is a tiny fraction of a CPU's silicon and power budget. Memory controllers, pipelining, and efficient superscalar instruction dispatch have far more effect, and Intel has a large lead on ARM in these areas.

"Memory controllers, pipelining, and efficient superscalar instruction dispatch have far more effect" Memory controllers(atleast the SOC(chip) level ones) are normally developed by the silicon vendor - like Nvidia, Broadcomm, Qualcomm, Samsung, TI, Freescale etc. Not ARM. And these companies have been working on it for many years. They have had graphics, video acceleration, display, camera-interface IPs all integrate…

Something is wrong Ranjith, you have more "dead" posts, you probably triggered something like "too many posts for a new account."

Hallo admins, Ranjith is the author of the linked article!

Re: Is Intel within ARM’s reach? Pedestrian Detection shows the way

#32

Post by ranjithparakkal »

mattst88 wrote: post #24
haricm wrote: post #11

Earlier quoted context omitted.

The model number used for the evaluation is Core™ i3-530

That's a Westmere from Jan 2010. Westmere -> Sandy Bridge -> Ivy Bridge -> Haswell. Comparing with something from 3.5 years and 3 generations ago is useful?

Copy pasting my reply once again.

You are right that the i3 CPU(Core i3-530) we compared with is a little old generation. I tried to compare online Core i3-530 with Core i3-2105. The 2105 is SandyBridge(couldnt find a direct comparison with an Ivy Bridge) and runs at a slightly higher clock 3.1 GHz(while the 530 runs at 2.93 according to CPU world).

According to cpu-world. The 2105 is 21% faster than the 530 for single threaded operations. If you account for the speed in clock this would mean only a boost of 14% improvement over the 530.

So its really not such a bad comparison.

In the meanwhile we will try run this on a newer CPU and let you know the results.

Re: Is Intel within ARM’s reach? Pedestrian Detection shows the way

#33

Post by ranjithparakkal »

jwise0 wrote: post #25

Sigh. Although some of this is Intel's own doing, "i3" is not a meaningful descriptor, especially when compared to "Cortex-A15" or "Cortex-A9". "Core i3" can refer to many, many generations of CPUs; this is not a nitpick, but a real complaint, because each of those CPUs have very different performance characteristics. Core i3 has been a Westmere (Nehalem tick); a Sandy Bridge; an Ivy Bridge (Sandy Bridge tick); and a…

You are right that the i3 CPU(Core i3-530) we compared with is a little old generation. I tried to compare online Core i3-530 with Core i3-2105. The 2105 is SandyBridge and runs at a slightly higher clock 3.1 GHz(while the 530 runs at 2.93 according to CPU world).

According to cpu-world. The 2105 is 21% faster than the 530 for single threaded operations. If you account for the speed in clock this would mean only a boost of 14% improvement over the 530.

So its really not such a bad comparison.

In the meanwhile we will try run this on a newer CPU and let you know the results.

Re: Is Intel within ARM’s reach? Pedestrian Detection shows the way

#34

Post by haricm »

berkut wrote: post #18
zurn wrote: post #3

Spoiler: no. 1265 ms vs 439 ms on their OpenCV benchmark. (Then they play some what-if games by underlocking the i3 in imaginative ways and applying SIMD opts to only the ARM side)

This. Assuming the compiler will generate good SSE code for the Intel CPU is a joke. If you write intrinsics for one arch, write it for both. I'd bet money the Intel side could be made 2.5-3x faster with proper SSE intrinsics and maybe 5-6x faster with a Haswell i3 using AVX (SandyBridge doesn't have the cache bandwidth to fully utilise AVX properly).

The original OpenCV code already has intrinsics in many portions of the code. But enabling them results only in a 10% improvement.

We decided to report non-intrinsics version, because reporting the original OpenCV numbers with intrinsics as SSE optimized would be unfair to Intel. Apparently its not very well optimized.

My own guess is that if we add intrinsics for Intel to our own C code, it will boost by around 2x. We could have written a blog without reporting the Intel C optimized numbers, but that would have been unfair to Intel again.

Re: Is Intel within ARM’s reach? Pedestrian Detection shows the way

#36

Post by haricm »

For those who are not convinced. Here is one more benchmark.

http://www.inpai.com.cn/doc/hard/198143_8.htm

Page takes a while to load. Then scroll down to the benchmarks. Take a look at the single threaded Linpack benchmarks between i7@3.5GHz and Exynos@1.6GHz.

Re: Is Intel within ARM’s reach? Pedestrian Detection shows the way

#37

Post by shameless_1 »

aristidb wrote: post #2

So code fully optimized for ARM/Cortex-A15 is almost as fast as only partially optimized code on a 1.2 GHz i3? Well, good to know I guess.

Not meant to counter your argument, but at least one compiler out there (GCC) is - in my experience - very good at finding optimizations for x86 but fails most of the time for ARM unless you provide very clear and very strict hints in your code. NEON optimization is one of them. It wouldn't be the first time that GCC completely ignores intrinsics in my loops or (I kid you not) introduces 16-bit Thumb code in my 32 bit code. Very frustrating to constantly have to second-guess your compiler.

Re: Is Intel within ARM’s reach? Pedestrian Detection shows the way

#38

Post by ksec »

You Cant Scale a Server/Desktop CPU two step down into Mobile Devices.

This is what Atom is all about, the higher power/performance x86 possible.

And You also cant scale a Mobile Devices up to a Server / Desktop Product.

That is what the ARMv8 Cortex A58 is all about, Low Power Desktop and Server Class.

So technically speaking both are marching towards each others end. Although Intel would lose out due to other factor such as business model.

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