I did what you said and I have a file GaussFit2D.ptx from nvcc and a file 
kernel.ptx from pyCuda.
GaussFit2D.ptx is 88 kB and kernel.ptx is 546 kB. I will show the top sections 
of the files:
 
GaussFit2D.ptx:
 
 .version 1.4
 .target sm_10, map_f64_to_f32
 // compiled with /usr/local/cuda/open64/lib//be
 // nvopencc 3.2 built on 2010-11-03
 
 //-----------------------------------------------------------
 // Compiling /tmp/tmpxft_000042fc_00000000-9_GaussFit2D_M2.cpp3.i 
(/tmp/ccBI#.fcgE6j)
 //-----------------------------------------------------------
 
 //-----------------------------------------------------------
 // Options:
 //-----------------------------------------------------------
 //  Target:ptx, ISA:sm_10, Endian:little, Pointer Size:64
 //  -O3 (Optimization level)
 //  -g0 (Debug level)
 //  -m2 (Report advisories)
 //-----------------------------------------------------------
 
 .file 1 "<command-line>"
 .file 2 "/tmp/tmpxft_000042fc_00000000-8_GaussFit2D_M2.cudafe2.gpu"
 .file 3 "/usr/lib/gcc/x86_64-linux-gnu/4.3.5/include/stddef.h"
 .file 4 "/usr/local/cuda/bin/../include/crt/device_runtime.h"
 .file 5 "/usr/local/cuda/bin/../include/host_defines.h"
 .file 6 "/usr/local/cuda/bin/../include/builtin_types.h"
 .file 7 "/usr/local/cuda/bin/../include/device_types.h"
 .file 8 "/usr/local/cuda/bin/../include/driver_types.h"
 .file 9 "/usr/local/cuda/bin/../include/surface_types.h"
 .file 10 "/usr/local/cuda/bin/../include/texture_types.h"
 .file 11 "/usr/local/cuda/bin/../include/vector_types.h"
 .file 12 "/usr/local/cuda/bin/../include/device_launch_parameters.h"
 .file 13 "/usr/local/cuda/bin/../include/crt/storage_class.h"
 .file 14 "/usr/include/bits/types.h"
 .file 15 "/usr/include/time.h"
 .file 16 "GaussFit2D_M2.cu"
 .file 17 "/usr/local/cuda/bin/../include/common_functions.h"
 .file 18 "/usr/local/cuda/bin/../include/math_functions.h"
 .file 19 "/usr/local/cuda/bin/../include/math_constants.h"
 .file 20 "/usr/local/cuda/bin/../include/device_functions.h"
 .file 21 "/usr/local/cuda/bin/../include/sm_11_atomic_functions.h"
 .file 22 "/usr/local/cuda/bin/../include/sm_12_atomic_functions.h"
 .file 23 "/usr/local/cuda/bin/../include/sm_13_double_functions.h"
 .file 24 "/usr/local/cuda/bin/../include/sm_20_atomic_functions.h"
 .file 25 "/usr/local/cuda/bin/../include/sm_20_intrinsics.h"
 .file 26 "/usr/local/cuda/bin/../include/surface_functions.h"
 .file 27 "/usr/local/cuda/bin/../include/texture_fetch_functions.h"
 .file 28 "/usr/local/cuda/bin/../include/math_functions_dbl_ptx1.h"

 .entry _Z6doFitsPfS_S_S_S_Pi (
  .param .u64 __cudaparm__Z6doFitsPfS_S_S_S_Pi_p,
...
...
kernel.ptx:
 
 .version 2.2
 .target sm_20
 // compiled with /usr/local/cuda/open64/lib//be
 // nvopencc 3.2 built on 2010-11-03
 
 //-----------------------------------------------------------
 // Compiling kernel.cpp3.i (/tmp/ccBI#.sl67va)
 //-----------------------------------------------------------
 
 //-----------------------------------------------------------
 // Options:
 //-----------------------------------------------------------
 //  Target:ptx, ISA:sm_20, Endian:little, Pointer Size:64
 //  -O3 (Optimization level)
 //  -g0 (Debug level)
 //  -m2 (Report advisories)
 //-----------------------------------------------------------
 
 .file 1 "<command-line>"
 .file 2 "kernel.cudafe2.gpu"
 .file 3 "/usr/lib/gcc/x86_64-linux-gnu/4.3.5/include/stddef.h"
 .file 4 "/usr/local/cuda/bin/../include/crt/device_runtime.h"
 .file 5 "/usr/local/cuda/bin/../include/host_defines.h"
 .file 6 "/usr/local/cuda/bin/../include/builtin_types.h"
 .file 7 "/usr/local/cuda/bin/../include/device_types.h"
 .file 8 "/usr/local/cuda/bin/../include/driver_types.h"
 .file 9 "/usr/local/cuda/bin/../include/surface_types.h"
 .file 10 "/usr/local/cuda/bin/../include/texture_types.h"
 .file 11 "/usr/local/cuda/bin/../include/vector_types.h"
 .file 12 "/usr/local/cuda/bin/../include/device_launch_parameters.h"
 .file 13 "/usr/local/cuda/bin/../include/crt/storage_class.h"
 .file 14 "/usr/include/bits/types.h"
 .file 15 "/usr/include/time.h"
 .file 16 "kernel.cu"
 .file 17 "/usr/local/cuda/bin/../include/common_functions.h"
 .file 18 "/usr/local/cuda/bin/../include/math_functions.h"
 .file 19 "/usr/local/cuda/bin/../include/math_constants.h"
 .file 20 "/usr/local/cuda/bin/../include/device_functions.h"
 .file 21 "/usr/local/cuda/bin/../include/sm_11_atomic_functions.h"
 .file 22 "/usr/local/cuda/bin/../include/sm_12_atomic_functions.h"
 .file 23 "/usr/local/cuda/bin/../include/sm_13_double_functions.h"
 .file 24 "/usr/local/cuda/bin/../include/sm_20_atomic_functions.h"
 .file 25 "/usr/local/cuda/bin/../include/sm_20_intrinsics.h"
 .file 26 "/usr/local/cuda/bin/../include/surface_functions.h"
 .file 27 "/usr/local/cuda/bin/../include/texture_fetch_functions.h"
 .file 28 "/usr/local/cuda/bin/../include/math_functions_dbl_ptx3.h"

 .visible .func gaussj (.param .u64 __cudaparmf1_gaussj, .param .u64 
__cudaparmf2_gaussj)
 {
 .reg .u32 %r<55>;
...
...
 
 
What does this mean?
Should they have been identical?
 
Michiel.
 
 

>>> Jonathan WRIGHT <[email protected]> 4/4/2012 3:01 PM >>>
Hello,

If you compile with the keep=True option you should find the ptx file 
generated by the compiler, eg:

In [127]: mod = SourceModule(s, keep=True )
*** compiler output in c:\users\wright\appdata\local\temp\tmpvzledt

Over in that folder I find "kernel.ptx" which contains the details of 
the nvcc compiler and options used and the assembler output. If you 
compile your C based kernel using nvcc and the -ptx option you should be 
able to diff the two outputs.

If the ptx files match and the timing still does not then you might want 
to try configuring pycuda with --cuda-trace as another way to track down 
the differences.

Cheers

Jon

On 04/04/2012 10:39, Michiel Bruinink wrote:
> Hello,
> I have written a Cuda program that calculates lots of Gauss fits. When I
> use that same program with PyCuda, the time it takes to do the
> calculations is almost 3x the time it takes with nvcc.
> With nvcc it takes 380 ms and with PyCuda it takes 1110 ms, while the
> outcome of the calculations is the same.
> There is no difference in the device code, because I use the same file
> for the device code in both cases.
> How is this possible?
> Does anybody have an idea?
> I am not sure, but could it have someting to do with array declarations
> inside a device function?
> # define lenP 6
> # define nPoints 100000
> ...
> __device__ void someFunction()
> {
> float residu[nPoints], newResidu[nPoints], pNew[lenP], b[lenP],
> deltaP[lenP];
> float A[lenP*lenP], Jacobian[nPoints*lenP], B[lenP*lenP];
> ...
> }
> Thanks,
> Michiel.
>
>
> _______________________________________________
> PyCUDA mailing list
> [email protected]
> http://lists.tiker.net/listinfo/pycuda

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