Why is N1's linpack score so much higher than droid?

[excalion]

I thought linpack was supposed to measure raw processor speed, which is capped? So why does N1 bench so much better than a droid if both are at 1ghz? It is because of intermediaries between the raw unprocessed data and the processor? By intermediaries, I mean stuff like JIT. So is the N1 just better engineered to utilize the 1ghz than the droid?

This isn't a bragging rights question, I'm just curious why it works the way it does.


Answer:

Your question was answered already...it comes down to processor architecture. Qualcomm's Snapdragon platform and more specifically the Scorpion application processor, while being related to TI's Omap Arm v7 series, has enhancements made by Qualcomm. The part of the cpu that handles the SIMD instructions has a wider pipeline, 128 bits vs 64 bits in TI's Omap. Scorpion also has a deeper pipeline to better handle all that data which I'd assume offsets some of the performance benefits a little bit.

As far as the difference between the two benchmarks, they are written to benchmark two different things. Linpack can run almost entirely within the SIMD/NEON portion of the cpu thereby showing off the enhancements made by Qualcomm. Quadrant stresses the entire core showing off total system performance showing that only in certain situations will Snapdragon outperform any other Arm v7 based core.

[compywiz]

Sort of guessing here, but I'd say part of the reason is because the clock speed isn't everything. A 1ghz ARM processor just doesn't have the same output as a 1ghz Snapdragon. Just because they are both at 1Ghz doesn't mean they will perform equally.

[jl8851]

You must be comparing an n1 on 2.2 to a droid on 2.1

OMAP processor on the X blows away the snapdragon


EDIT: Thought you were talking about the X, nevermind

[excalion]

Sort of guessing here, but I'd say part of the reason is because the clock speed isn't everything. A 1ghz ARM processor just doesn't have the same output as a 1ghz Snapdragon. Just because they are both at 1Ghz doesn't mean they will perform equally.

Yea that's understandable.

What I don't understand is why a 1.25ghz droid can score about the same as an N1 on quadrant processor benchmarks, but only get ~19 mflops when N1 gets 35+.

________________quadrant(processor score)______________________linpack
droid(2.2)________________5788____________________ __________~19 mflops

N1(2.2)_________________~5500(source)_______________________35+ mflops


This is what I don't get.

[SwiftLegend]

Different hardware means different results. That's like comparing a stock Intel CPU to a stock ATI, the Intel will most likely win.

[excalion]

Different hardware means different results. That's like comparing a stock Intel CPU to a stock ATI, the Intel will most likely win.

I'm not asking IF different hardware means different results. I'm asking WHY different hardware means different results when they are both at the same speed? As I understand it, the electrons running through the processor chip turns many "nodes" inside the processor on and off. The speed at which these electrons flow through the chip is the clock speed(X mhz).

So if both chips are having their nodes turned on and off at the same rate/speed, why is one faster than the other? The only possible conclusion I can see lies in the difference between the efficiency of an "intermediary" between the raw data and the processing unit. Does such an intermediary exist? If it possible to access this portion of the processor through conventional means? Why is the droid's intermediary running at half the efficiency of N1's?(According to linpack) These are the questions I'm asking.

[lockdownx1x]

Two Words: CPU Architecture. GHz mean nothing.

[SwiftLegend]

Two Words: CPU Architecture. GHz mean nothing.

Exactly. Like I said, different hardware means different results, asking why is kinda >.>. Again with the computer analogy, a 1.2GHz Intel in a Mac vs. a 1.2GHz ATI in a PC, the Mac will surely win. Different companies build their products different, thats what causes competition.
A Snapdragon is a higher grade cpu unlike the ARM. If I remember correctly, the Droid is supposed to run at 550 mhz, and we are overclocking it to 1 GHz, you're soft-modding the CPU. You really think a 550 MHz processor forced to run at 1 GHz can compare to an originally 1 GHz processor?

[takeshi]

The only possible conclusion I can see lies in the difference between the efficiency of an "intermediary" between the raw data and the processing unit.

Faulty assumption. Processor architecture absolutely matters. Clock speed is just clock speed.

You really think a 550 MHz processor forced to run at 1 GHz can compare to an originally 1 GHz processor?

There's also a faulty assumption there. It's certainly possible.

[excalion]

Two Words: CPU Architecture. GHz mean nothing.

Exactly. Like I said, different hardware means different results, asking why is kinda >.>. Again with the computer analogy, a 1.2GHz Intel in a Mac vs. a 1.2GHz ATI in a PC, the Mac will surely win. Different companies build their products different, thats what causes competition.
A Snapdragon is a higher grade cpu unlike the ARM. If I remember correctly, the Droid is supposed to run at 550 mhz, and we are overclocking it to 1 GHz, you're soft-modding the CPU. You really think a 550 MHz processor forced to run at 1 GHz can compare to an originally 1 GHz processor?

Two things.
1. The reasons why droids are clocked at 550mhz instead of 1ghz are many, but the limitations of the chip itself are NOT one of them.

2. Quadrant benchmarks both chips to be about the same. So yes, a 550mhz OC'd chip CAN run just as well as an originally 1ghz chip.

I appreciate you trying to help, but seriously though, if I just wanted some very vague and basic answers I'd just google it. I'm looking for an answer from an electrical engineering perspective. Are there any tech gurus out there who can answer this question with elaborate details?

The only possible conclusion I can see lies in the difference between the efficiency of an "intermediary" between the raw data and the processing unit.

Faulty assumption. Processor architecture absolutely matters. Clock speed is just clock speed.

So why can't the CPU architecture be the intermediary between the nodes being turned on and off by the electrons, and the raw unprocessed data? How is my assumption a faulty one?