void jacobi(
crs_matrix<double> const & A
, std::vector<double> const & b
, std::size_t iterations
, std::size_t block_size
)
{
typedef std::vector<double> vector_type;
boost::shared_ptr<vector_type> dst(new vector_type(b));
boost::shared_ptr<vector_type> src(new vector_type(b));
std::vector<range> block_ranges;
// pre-computing ranges for the different blocks
for(std::size_t i = 0; i < dst->size(); i += block_size)
{
block_ranges.push_back(
range(i, std::min<std::size_t>(dst->size(), i + block_size)));
}
// pre-computing dependencies
std::vector<std::vector<std::size_t> > dependencies(block_ranges.size());
for(std::size_t b = 0; b < block_ranges.size(); ++b)
{
for(std::size_t i = block_ranges[b].begin(); i < block_ranges[b].end(); ++i)
{
std::size_t begin = A.row_begin(i);
std::size_t end = A.row_end(i);
for(std::size_t ii = begin; ii < end; ++ii)
{
std::size_t idx = A.indices[ii];
for(std::size_t j = 0; j < block_ranges.size(); ++j)
{
if(block_ranges[j].begin() <= idx && idx < block_ranges[j].end())
{
if(std::find(dependencies[b].begin(), dependencies[b].end(), j) == dependencies[b].end())
{
dependencies[b].push_back(j);
}
break;
}
}
}
}
}
typedef std::vector<hpx::shared_future<void> > future_vector;
boost::shared_ptr<future_vector> deps_dst(new future_vector(dependencies.size(), hpx::make_ready_future()));
boost::shared_ptr<future_vector> deps_src(new future_vector(dependencies.size(), hpx::make_ready_future()));
hpx::util::high_resolution_timer t;
for(std::size_t iter = 0; iter < iterations; ++iter)
{
for(std::size_t block = 0; block < block_ranges.size(); ++block)
{
std::vector<std::size_t> const & deps(dependencies[block]);
std::vector<hpx::shared_future<void> > trigger;
trigger.reserve(deps.size());
for (std::size_t dep : deps)
{
trigger.push_back((*deps_src)[dep]);
}
(*deps_dst)[block]
= hpx::when_all(boost::move(trigger)).then(
hpx::launch::async,
hpx::util::bind(
jacobi_kernel_wrap
, block_ranges[block]
, boost::cref(A)
, boost::ref(*dst)
, boost::cref(*src)
, boost::cref(b)
)
);
}
std::swap(dst, src);
std::swap(deps_dst, deps_src);
}
hpx::wait_all(*deps_dst);
hpx::wait_all(*deps_src);
double time_elapsed = t.elapsed();
std::cout << dst->size() << " "
<< ((double(dst->size() * iterations)/1e6)/time_elapsed) << " MLUPS/s\n"
<< std::flush;
}