Performance Comparison: Sun Studio vs GCC on STREAM Benchmark

I have previously described  the STREAM Benchmark and the results we were seeing with its OpenMP version and what we got by turning on Automatic Parallelization  in the compiler.
Here I'd like to put out comparative results with the GCC compiler

Function
Sun Studio 11(MB/s)
GCC4.1 (MB/s)
Copy
4658
2766
Scale
4614
2745
Add
4628
2970
Triad
4627
2969

This is roughly a 1.6x advantage with the Sun Studio compiler.
The comparisons were done on exactly the same box. The box was a SunFire V40z with 4 x 2.6GHz processors and PC3200 CL3 DDR SDRAM ECC Regd. memory.

The Optimization options used in these cases were:
Sun Studio: -fast -xarch=amd64a -xvector=simd -xprefetch -xprefetch_level=3
GCC 4.1: -O3 -funroll-all-loops -ffast-math -fpeephole -m64 -mtune=k8 -fprefetch-loop-arrays

Function
Sun Studio 11(MB/s)
Sun Studio 11(MB/s)
 4proc  Autopar
Copy
4658
18120
Scale
4614
18108
Add
4628
17758
Triad
4627
17626

For a 4CPU machine, this is roughly a 3.9x scalability, which is incredible!
Of course, the GCC compiler isnt able to exploit such scalability because it does neither Automatic Parallelization nor OpenMP at this time. (Its working on at least OpenMP support, so at least this discrepancy will be addressed in a future release.).
Comments:

I wonder how those 2 compilers stack up with Intel compiler (ICC) which is also quite smart.

Posted by Mike on October 18, 2006 at 12:32 PM PDT #

The numbers with Intel's compiler is roughly about 10% lower than SunStudio.
I used -fast -auto_ilp32 -IPF_fp_relaxed -openmp on the icc (Intel) compiler, which seemed "peak" for this benchmark. It scales equally and is 10% for 1-, 2- and 4 thread versions behind the numbers I have shown here.

Posted by guest on October 20, 2006 at 09:14 AM PDT #

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I have worked with Sun and Oracle for 25 years now; in compilers and tools organization for most of these years followed by a couple of years in Cloud Computing. I am now in ISV Engineering, where our primary task is to improve synergy between Oracle Sun Systems and our rich ISV ecosystem

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