Re: [atlas-devel] OpenMP settings

[R. C. W. <rcw...@ls...>]

OK, I sped things up a bit by turning off PCA panel factorization in 
both LU and QR.  I also installed 3.10.2, and it is even slower than 
3.11.29 on the same systems.  So, I guess my new stuff is working as 
well as it ever did with OpenMP, which is not well at all.

I know some folks use OpenMP, and the question now is if they ever got 
good results that way.  Please let me know if you use ATLAS wt OpenMP.

Thanks,
Clint

On 08/06/2014 04:46 PM, R. Clint Whaley wrote:
> Guys,
>
> I know some of you tend to compile ATLAS with OpenMP because you have
> applications that use OpenMP.  When you have done that in the past, what
> environment variables do you typically set?
>
> The reason I ask is that I'm trying to re-enable OpenMP as an option in
> the developer series, and I now have something that builds, but the
> performance is often worse than serial.  Here's a run comparing
> cholesky, LU, and QR using pthreads on a 32-core opteron using my
> pthreads blas:
>
> -- ORD  UPLO       N    NRHS     lda     ldb       TIME     MFLOP
>    RESID
> ===  ====  ======  ======  ======  ======  =========  ========  ===========
>
>     C     U    2000       1    2000    2000      0.074  36101.60
> 2.344654e-04
>     C     G    2000       1    2000    2000      0.207  25803.12
> 2.080718e-02
>     C     Q    2000       1    2000    2000      0.397  26863.33
> 6.125385e-03ORD
>
>
> Now here's with my OpenMP blas:
>    UPLO       N    NRHS     lda     ldb       TIME
>
>
> MFLOP        RESID
> ===  ====  ======  ======  ======  ======  =========  ========  ===========
>
>     C     U    2000       1    2000    2000      0.108  24837.22
> 2.344654e-04
>     C     G    2000       1    2000    2000     16.977    314.51
> 4.030246e-02
>     C     Q    2000       1    2000    2000     41.308    258.32
> 5.260133e-03
>
>
> I've tried setting OMP_PROC_BIND to both true and false, and also
> setting GOMP_CPU_AFFINITY to "0-31", and I still get these results.
>
> It's probably a bug in my OpenMP implementation; I'll install 3.10 on
> the same system with OpenMP, and see what I get with that, but if you
> have some environment variables I should set, please let me know.
>
> If it matters, the two machines I'm using are a 32-core AMD Opteron 6128
> and a 12-core Intel Xeon E5645.
>
> Thanks,
> Clint
>
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> ** R. Clint Whaley, PhD * Assoc Prof, LSU * www.csc.lsu.edu/~whaley **
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-- 
**********************************************************************
** R. Clint Whaley, PhD * Assoc Prof, LSU * www.csc.lsu.edu/~whaley **
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