AVX- holy cow!

jtr1962

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Reading recently about CPU architecture and processor floating point performance, I was actually stoked to learn my new A10-5800K has AVX capability. It turns out AVX actually works exceedingly well in the real world. Here's Intel Burn Test with a regular (SSE?) floating point Linpack:



And here's the same test using AVX:



My results with AVX seemed to vary much more than with SSE. I was consistently getting about 20.3 GFlops with SSE. With AVX, I was getting anywhere from about 43 up to 46.8 GFlops. Results during any one run would be consistent, but the very next run would be different.

In a nutshell, AVX allows the CPU to do 8 double-precision (or 16 single-precision) floating point operations per clock cycle per core. This is twice the throughput of SSE. OK, two cores share a floating-point unit in Trinity, so maximum theoretical throughput in Intel Burn Test or Linx is 2x8xclock speed (4GHz in my case), or 64 double-precision GFlops. I'm actually getting more than twice the speed using AVX as opposed to SSE. And I read that Intel's new Haswell will use AVX2, which is theoretically twice the speed of AVX.

Anyway, I thought I would share these results because they're pretty amazing. 45+ GFlops may not be a speed champion by today's standards, but if I could take my new machine back in time to the early 1990s, it would have been the fastest thing around. Now if only more software would use AVX, especially train sims which by their nature do lots of FP calculations.
 

LunarMist

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I'm not sure what AVX is or whether my CPU has that option, but my 2 1/2-year-old computer produces 90 GFlops avg.
I wonder what a current CPU can do. Perhaps Dave is at 200 already.
 

jtr1962

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CPUs with AVX

If your GFlops is more than number of cores x 4 x frequency in GHz then your processor has AVX. It sounds like your CPU has AVX. Even a 6 core CPU will have a hard time hitting 90 GFlops without it.

I don't think any desktop CPU has hit 200 yet, but I've seen numbers in the 130 to 140 range for the top of the line Intel 6-core CPUs. Haswell should get us well past 200, even with only 4 cores.
 

LunarMist

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CPUs with AVX

If your GFlops is more than number of cores x 4 x frequency in GHz then your processor has AVX. It sounds like your CPU has AVX. Even a 6 core CPU will have a hard time hitting 90 GFlops without it.

I don't think any desktop CPU has hit 200 yet, but I've seen numbers in the 130 to 140 range for the top of the line Intel 6-core CPUs. Haswell should get us well past 200, even with only 4 cores.
I have the i7-980X (6 cores), so maybe not. I need a substantial increase in the real-world performance to upgrade, and that is often less than linear with benchmarks. I guess we have to wait a while for the next gen of 6-8 core CPUs.
 

jtr1962

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I have the i7-980X (6 cores), so maybe not. I need a substantial increase in the real-world performance to upgrade, and that is often less than linear with benchmarks. I guess we have to wait a while for the next gen of 6-8 core CPUs.
I have the same mindset. I generally won't even consider an upgrade unless the new stuff benchmarks at least ten times what I'm using. I actually did better than that with this upgrade-going from about 1.2 GFlops with my XP3200 to 45+ GFlops. I probably won't get upgrade fever again until we have 1 TFlop CPUs.

Incidentally, it's a pity Intel Burn Test can't use the integrated GPU. AMD says the GPU can do 768 single-precision flops per clock cycle. I'm currently at 894 MHz, so that's another ~687 GFlops (single precision). I don't think the GPU hardware can do double-precision.
 

LunarMist

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I have the same mindset. I generally won't even consider an upgrade unless the new stuff benchmarks at least ten times what I'm using.
I think a full upgrade every three years or 2x performance increase is about right. It helps to start with the fastest CPU of the time.
 

CougTek

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I think a full upgrade every three years or 2x performance increase is about right. It helps to start with the fastest CPU of the time.
For you, the next upgrade probably won't be before the Ivy Bridge E processors launch at the end of August or during September this year. There should be 10 or even 12 cores variants and with the improved IPC, you should get your 2x performance versus your current i7 980X.

What I'd like to know now is if the FAH client uses AVX or not. Probably not.
 

Stereodude

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Reading recently about CPU architecture and processor floating point performance, I was actually stoked to learn my new A10-5800K has AVX capability. It turns out AVX actually works exceedingly well in the real world.
And what application do you run that uses AVX?
 

LunarMist

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My little 3 lb. laptop with i5 yields a 38 score, but runs quite hot. :erm:
 
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