Commit b06297bb authored by Jakub Klinkovský's avatar Jakub Klinkovský
Browse files

Prefetching and unrolling does not help for vector addition according to benchmarks

parent 04e118e9

src/TNL/Containers/Algorithms/VectorOperationsHost_impl.h

+0 −37
Original line number Diff line number Diff line
@@ -520,42 +520,6 @@ addVector( Vector1& y, 


   const Index n = y.getSize();



#ifdef OPTIMIZED_VECTOR_HOST_OPERATIONS

#ifdef __GNUC__

   // We need to get the address of the first element to avoid

   // bounds checking in TNL::Array::operator[]

   typedef typename Vector1::RealType Real;   

         Real* Y = y.getData();

   const Real* X = x.getData();

#endif



   Index i = 0;

   const Index unroll_limit = n - n % 4;

#ifdef HAVE_OPENMP

   #pragma omp parallel for \

      if( n > OpenMPVectorOperationsThreshold ) \

      lastprivate(i)

#endif

   for(i = 0; i < unroll_limit; i += 4)

   {

#ifdef __GNUC__

      __builtin_prefetch(&y[ i + PrefetchDistance ], 1, 0);

      __builtin_prefetch(&x[ i + PrefetchDistance ], 0, 0);

#endif

      y[ i ]     = thisMultiplicator * y[ i ]     + alpha * x[ i ];

      y[ i + 1 ] = thisMultiplicator * y[ i + 1 ] + alpha * x[ i + 1 ];

      y[ i + 2 ] = thisMultiplicator * y[ i + 2 ] + alpha * x[ i + 2 ];

      y[ i + 3 ] = thisMultiplicator * y[ i + 3 ] + alpha * x[ i + 3 ];

   }



   while( i < n )

   {

      y[i] = thisMultiplicator * y[ i ] + alpha * x[ i ];

      i++;

   }



#else // OPTIMIZED_VECTOR_HOST_OPERATIONS



   if( thisMultiplicator == 1.0 )

#ifdef HAVE_OPENMP

#pragma omp parallel for if( TNL::Devices::Host::isOMPEnabled() && n > OpenMPVectorOperationsThreshold ) // TODO: check this threshold
@@ -568,7 +532,6 @@ addVector( Vector1& y, 
#endif

      for( Index i = 0; i < n; i ++ )

         y[ i ] = thisMultiplicator * y[ i ] + alpha * x[ i ];

#endif // OPTIMIZED_VECTOR_HOST_OPERATIONS

}



template< typename Vector1,