[Starpu-devel] CUDA task and GCC plugin

[Mehdi AMINI <mehdi.amini@silkan.com>]

Hello,

I'm trying to play with mixing CUDA task and the GCC plugin, using the 
StarPU 1.0.1 tar.gz online.

First I wonder if I can declare a task with only a CUDA implementation 
and no CPU implementation ? Currently I always end up with a linker error.

I also wonder if there is a more verbose mode for StarPU ? Using 
--enable-debug and --enable-verbose juste give some initialization 
informations but I would also expect an output each time a task or a 
data transfer is scheduled.

I also have an issue related to implicit cpu implementations and -O3 gcc 
flag which seems to be broken. I'm testing a simple task call with a CPU 
and a CUDA implementation. Using -O3 the CPU task is always executed 
while without the -O3 flag the CUDA task is correctly executed. Is it a 
known issue ?
The issue doesn't occur with explicit tasks.

See attached to reproduce the issue (it took me a loooooong time to spot 
the origin of this issue...):

$ OPT_FLAG=-O2 ./compile-test.sh
[....]
Run with implicit CPU task, compiled and link at the same time
GPU !
Run with implicit CPU task, compiled and link separately
GPU !
Run with explicit CPU task, compiled and link at the same time
GPU !
Run with explicit CPU task, compiled and link separately
GPU !

$ OPT_FLAG=-O3 ./compile-test.sh
[...]
Run with implicit CPU task, compiled and link at the same time
*CPU*
Run with implicit CPU task, compiled and link separately
*CPU*
Run with explicit CPU task, compiled and link at the same time
GPU !
Run with explicit CPU task, compiled and link separately
GPU !


Best,

Mehdi



PS: I use a fedora core 16,

# StarPU configuration
$ ./config.status --config
'--disable-cpu' '--prefix=/home/amini/StarPU/starpu-install/' 
'--with-cuda-dir=/opt/cuda/' '--with-cuda-lib-dir=/usr/lib64/nvidia' 
'LDFLAGS=-L/usr/lib64/nvidia/'

# GCC Version
$ gcc -v
Utilisation des specs internes.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/4.6.3/lto-wrapper
Target: x86_64-redhat-linux
Configuré avec: ../configure --prefix=/usr --mandir=/usr/share/man 
--infodir=/usr/share/info 
--with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap 
--enable-shared --enable-threads=posix --enable-checking=release 
--with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions 
--enable-gnu-unique-object --enable-linker-build-id 
--enable-languages=c,c++,objc,obj-c++,java,fortran,ada,go,lto 
--enable-plugin --enable-java-awt=gtk --disable-dssi 
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre 
--enable-libgcj-multifile --enable-java-maintainer-mode 
--with-ecj-jar=/usr/share/java/eclipse-ecj.jar 
--disable-libjava-multilib --with-ppl --with-cloog --with-tune=generic 
--with-arch_32=i686 --build=x86_64-redhat-linux
Modèle de thread: posix
gcc version 4.6.3 20120306 (Red Hat 4.6.3-2) (GCC)

#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <math.h>


#define NX 512
double A[NX];
double B[NX];
double E[NX];


static void launcher(const double A[NX], const double B[NX], double E[NX], 
                  int nx)
  __attribute__ ((task));

#ifndef IMPLICIT
static void launcher_cpu(const double A[NX], const double B[NX], double E[NX], 
                  int nx)
  __attribute__ ((task_implementation ("cpu", launcher)));
static void launcher_cpu(const double A[NX], const double B[NX], double E[NX], 
                  int nx)
#else
static void launcher(const double A[NX], const double B[NX], double E[NX], 
                  int nx)
#endif
{
 printf("CPU\n");
}


extern void launcher_cuda(const double A[NX], const double B[NX], double E[NX], 
                  int nx)
  __attribute__ ((task_implementation ("cuda", launcher)));


int main(int argc, char **argv)
{
   int nx = NX;
   
      
#pragma starpu initialize

#pragma starpu register A
#pragma starpu register B
#pragma starpu register E
   

   launcher((double *)A, (double *)B, (double *)E, nx);
   
#pragma starpu wait

#pragma starpu unregister E

   return 0;
}

Attachment: kernel.cu
Description: application/cu-seeme

Attachment: compile-test.sh
Description: application/shellscript