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Transforms omp loop to reduction

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This commit is contained in:
Yannis Mentekidis
2016-07-08 14:23:24 +01:00
parent b92d46527c
commit 2fee61e28c
2 changed files with 42 additions and 33 deletions
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CMakeLists.txt
+3
View File
@@ -238,10 +238,13 @@ add_definitions(-DBOOST_TEST_DYN_LINK)
# If OpenMP is found, define HAS_OPENMP to be 1. Otherwise define it to be 0.
find_package(OpenMP)
if (OPENMP_FOUND)
add_definitions(-DHAS_OPENMP)
set(HAS_OPENMP 1)
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
else ()
add_definitions(-DHAS_OPENMP)
set(HAS_OPENMP 0)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-unknown-pragmas")
endif ()
src/mlpack/methods/lsh/lsh_search_impl.hpp
+39 -33
View File
@@ -373,8 +373,8 @@ bool LSHSearch<SortPolicy>::PerturbationShift(std::vector<bool>& A) const
for (size_t i = 0; i < A.size(); ++i)
if (A[i] == 1) // marked true
maxPos=i;
if ( maxPos + 1 < A.size()) // otherwise, this is an invalid vector
if ( maxPos + 1 < A.size()) // otherwise, this is an invalid vector
{
A[maxPos] = 0;
A[maxPos + 1] = 1;
@@ -445,8 +445,8 @@ void LSHSearch<SortPolicy>::GetAdditionalProbingBins(
// Each column of additionalProbingBins is the code of a bin.
additionalProbingBins.set_size(numProj, T);
// Copy the query's code, then in the end we will add/subtract according
// Copy the query's code, then in the end we will add/subtract according
// to perturbations we calculated.
for (size_t c = 0; c < T; ++c)
additionalProbingBins.col(c) = queryCode;
@@ -497,7 +497,7 @@ void LSHSearch<SortPolicy>::GetAdditionalProbingBins(
minloc = s;
}
}
// Add or subtract 1 to dimension corresponding to minimum score.
additionalProbingBins(positions[minloc], 0) += actions[minloc];
if (T == 1)
@@ -512,7 +512,7 @@ void LSHSearch<SortPolicy>::GetAdditionalProbingBins(
// smallest and the second smallest, it's obvious that score(Ae) >
// score(As). Therefore the second perturbation vector is ALWAYS the vector
// containing only the second-lowest scoring perturbation.
double minscore2 = scores[0];
size_t minloc2 = 0;
for (size_t s = 0; s < (2 * numProj); ++s) // here we can't start from 1
@@ -590,13 +590,13 @@ void LSHSearch<SortPolicy>::GetAdditionalProbingBins(
{
perturbationSets.push_back(As); // add shifted set to sets
minHeap.push(
std::make_pair(PerturbationScore(As, scores),
std::make_pair(PerturbationScore(As, scores),
perturbationSets.size() - 1));
}
// Expand operation on Ai (add max+1 to set).
std::vector<bool> Ae = Ai;
if (PerturbationExpand(Ae) && PerturbationValid(Ae))
if (PerturbationExpand(Ae) && PerturbationValid(Ae))
// Don't add invalid sets.
{
perturbationSets.push_back(Ae); // add expanded set to sets
@@ -610,7 +610,7 @@ void LSHSearch<SortPolicy>::GetAdditionalProbingBins(
// Found valid perturbation set Ai. Construct perturbation vector from set.
for (size_t pos = 0; pos < Ai.size(); ++pos)
// If Ai[pos] is marked, add action to probing vector.
additionalProbingBins(positions(pos), pvec)
additionalProbingBins(positions(pos), pvec)
+= Ai[pos] ? actions(pos) : 0;
}
}
@@ -808,13 +808,13 @@ void LSHSearch<SortPolicy>::Search(const arma::mat& querySet,
{
Teffective = (1 << numProj) - 1;
Log::Warn << "Requested " << T << " additional bins are more than "
<< "theoretical maximum. Using " << Teffective << " instead."
<< "theoretical maximum. Using " << Teffective << " instead."
<< std::endl;
}
// If the user set multiprobe, log it
if (Teffective > 0)
Log::Info << "Running multiprobe LSH with " << Teffective
Log::Info << "Running multiprobe LSH with " << Teffective
<<" additional probing bins per table per query." << std::endl;
size_t avgIndicesReturned = 0;
@@ -822,16 +822,20 @@ void LSHSearch<SortPolicy>::Search(const arma::mat& querySet,
Timer::Start("computing_neighbors");
// Parallelization to process more than one query at a time.
#pragma omp parallel for \
shared(avgIndicesReturned, resultingNeighbors, distances) \
schedule(dynamic)
#ifdef _WIN32
// Tiny workaround: Visual Studio only implements OpenMP 2.0, which doesn't
// support unsigned loop variables. If we're building for Visual Studio, use
// the intmax_t type instead.
intmax_t querySetSize = (intmax_t) querySet.n_cols;
for (intmax_t i = 0; i < querySetSize; ++i)
#pragma omp parallel for \
shared(resultingNeighbors, distances) \
schedule(dynamic)\
reduction(+:avgIndicesReturned)
for (intmax_t i = 0; i < (intmax_t) querySet.n_cols; ++i)
#else
#pragma omp parallel for \
shared(resultingNeighbors, distances) \
schedule(dynamic)\
reduction(+:avgIndicesReturned)
for (size_t i = 0; i < querySet.n_cols; ++i)
#endif
{
@@ -839,14 +843,14 @@ void LSHSearch<SortPolicy>::Search(const arma::mat& querySet,
// Hash every query into every hash table and eventually into the
// 'secondHashTable' to obtain the neighbor candidates.
arma::uvec refIndices;
ReturnIndicesFromTable(querySet.col(i), refIndices, numTablesToSearch,
ReturnIndicesFromTable(querySet.col(i), refIndices, numTablesToSearch,
Teffective);
// An informative book-keeping for the number of neighbor candidates
// returned on average.
// Make atomic to avoid race conditions when multiple threads are running
#pragma omp atomic
avgIndicesReturned += refIndices.n_elem;
// #pragma omp atomic
avgIndicesReturned = avgIndicesReturned + refIndices.n_elem;
// Sequentially go through all the candidates and save the best 'k'
// candidates.
@@ -883,7 +887,7 @@ Search(const size_t k,
{
Teffective = (1 << numProj) - 1;
Log::Warn << "Requested " << T << " additional bins are more than "
<< "theoretical maximum. Using " << Teffective << " instead."
<< "theoretical maximum. Using " << Teffective << " instead."
<< std::endl;
}
@@ -891,28 +895,30 @@ Search(const size_t k,
if (T > 0)
Log::Info << "Running multiprobe LSH with " << Teffective <<
" additional probing bins per table per query."<< std::endl;
size_t avgIndicesReturned = 0;
Timer::Start("computing_neighbors");
// Parallelization to process more than one query at a time.
#pragma omp parallel for \
shared(avgIndicesReturned, resultingNeighbors, distances) \
schedule(dynamic)
#ifdef _WIN32
// Tiny workaround: Visual Studio only implements OpenMP 2.0, which doesn't
// support unsigned loop variables. If we're building for Visual Studio, use
// the intmax_t type instead.
intmax_t referenceSetSize = (intmax_t) referenceSet->n_cols;
for (intmax_t i = 0; i < referenceSetSize; ++i)
#pragma omp parallel for \
shared(resultingNeighbors, distances) \
schedule(dynamic)\
reduction(+:avgIndicesReturned)
for (intmax_t i = 0; i < (intmax_t) referenceSet->n_cols; ++i)
#else
#pragma omp parallel for \
shared(resultingNeighbors, distances) \
schedule(dynamic)\
reduction(+:avgIndicesReturned)
for (size_t i = 0; i < referenceSet->n_cols; ++i)
#endif
// Go through every query point. Use long int because some compilers complain
// for openMP unsigned index variables.
for (size_t i = 0; i < referenceSet->n_cols; i++)
{
// Go through every query point.
// Hash every query into every hash table and eventually into the
// 'secondHashTable' to obtain the neighbor candidates.
arma::uvec refIndices;
@@ -920,10 +926,10 @@ Search(const size_t k,
Teffective);
// An informative book-keeping for the number of neighbor candidates
// returned on average. Make atomic to avoid race conditions when multiple
// threads are running.
#pragma omp atomic
avgIndicesReturned += refIndices.n_elem;
// returned on average.
// Make atomic to avoid race conditions when multiple threads are running.
// #pragma omp atomic
avgIndicesReturned = avgIndicesReturned + refIndices.n_elem;
// Sequentially go through all the candidates and save the best 'k'
// candidates.