System information

Intel® Xeon Phi™ Coprocessor DEVELOPER’S QUICK START GUIDE

Code Example 10: Wrapping the Intel TBB Header Files in C/C++

Functions called from within the offloaded construct and global data required on the Intel® Xeon Phi™

Coprocessor should be appended by the special function attribute __attribute__((target(mic))).

As an example, parallel_reduce recursively splits an array into subranges for each thread to work on. The

parallel_reduce uses a splitting constructor to make one or more copies for each thread. For each split, the

method join is invoked to accumulate the results.

1. Prefix the class by the macro __MIC__ and the class name by __attribute__((target(mic))) if

you want them to be generated for the coprocessor.

#ifdef __MIC__

class __attribute__((target(mic))) ReduceTBB

{

private:

float *my_data;

public:

float sum;

void operator()( const blocked_range<size_t>& r )

{

float *data = my_data;

for( size_t i=r.begin(); i!=r.end(); ++i)

{

sum += data[i];

}

ReduceTBB( ReduceTBB& x, split) : my_data(x.my_data), sum(0) {}

void join( const ReduceTBB& y) { sum += y.sum; }

ReduceTBB( float data[] ) : my_data(data), sum(0) {}

};

#endif

Code Example 11: Prefixing an Intel TBB Class for Intel® MIC Architecture code generation in C/C++

2. Prefix the function to be offloaded to the Intel® Xeon Phi™ Coprocessor by

__attribute__((target(mic)))

float MICReductionTBB(float *data, int size)

{

ReduceTBB redc(data);

// initializing the library

task_scheduler_init init;

parallel_reduce(blocked_range<size_t>(0, size), redc);

return redc.sum;

}