diff options
Diffstat (limited to 'Eigen/src/Core/products/Parallelizer.h')
| -rw-r--r-- | Eigen/src/Core/products/Parallelizer.h | 25 |
1 files changed, 20 insertions, 5 deletions
diff --git a/Eigen/src/Core/products/Parallelizer.h b/Eigen/src/Core/products/Parallelizer.h index c0ddc0c06..8f91879e4 100644 --- a/Eigen/src/Core/products/Parallelizer.h +++ b/Eigen/src/Core/products/Parallelizer.h @@ -10,7 +10,9 @@ #ifndef EIGEN_PARALLELIZER_H #define EIGEN_PARALLELIZER_H +#if EIGEN_HAS_CXX11_ATOMIC #include <atomic> +#endif namespace Eigen { @@ -19,7 +21,8 @@ namespace internal { /** \internal */ inline void manage_multi_threading(Action action, int* v) { - static EIGEN_UNUSED int m_maxThreads = -1; + static int m_maxThreads = -1; + EIGEN_UNUSED_VARIABLE(m_maxThreads) if(action==SetAction) { @@ -77,8 +80,17 @@ template<typename Index> struct GemmParallelInfo { GemmParallelInfo() : sync(-1), users(0), lhs_start(0), lhs_length(0) {} + // volatile is not enough on all architectures (see bug 1572) + // to guarantee that when thread A says to thread B that it is + // done with packing a block, then all writes have been really + // carried out... C++11 memory model+atomic guarantees this. +#if EIGEN_HAS_CXX11_ATOMIC std::atomic<Index> sync; std::atomic<int> users; +#else + Index volatile sync; + int volatile users; +#endif Index lhs_start; Index lhs_length; @@ -89,11 +101,14 @@ void parallelize_gemm(const Functor& func, Index rows, Index cols, Index depth, { // TODO when EIGEN_USE_BLAS is defined, // we should still enable OMP for other scalar types -#if !(defined (EIGEN_HAS_OPENMP)) || defined (EIGEN_USE_BLAS) + // Without C++11, we have to disable GEMM's parallelization on + // non x86 architectures because there volatile is not enough for our purpose. + // See bug 1572. +#if (! defined(EIGEN_HAS_OPENMP)) || defined(EIGEN_USE_BLAS) || ((!EIGEN_HAS_CXX11_ATOMIC) && !(EIGEN_ARCH_i386_OR_x86_64)) // FIXME the transpose variable is only needed to properly split // the matrix product when multithreading is enabled. This is a temporary // fix to support row-major destination matrices. This whole - // parallelizer mechanism has to be redisigned anyway. + // parallelizer mechanism has to be redesigned anyway. EIGEN_UNUSED_VARIABLE(depth); EIGEN_UNUSED_VARIABLE(transpose); func(0,rows, 0,cols); @@ -114,12 +129,12 @@ void parallelize_gemm(const Functor& func, Index rows, Index cols, Index depth, double work = static_cast<double>(rows) * static_cast<double>(cols) * static_cast<double>(depth); double kMinTaskSize = 50000; // FIXME improve this heuristic. - pb_max_threads = std::max<Index>(1, std::min<Index>(pb_max_threads, work / kMinTaskSize)); + pb_max_threads = std::max<Index>(1, std::min<Index>(pb_max_threads, static_cast<Index>( work / kMinTaskSize ) )); // compute the number of threads we are going to use Index threads = std::min<Index>(nbThreads(), pb_max_threads); - // if multi-threading is explicitely disabled, not useful, or if we already are in a parallel session, + // if multi-threading is explicitly disabled, not useful, or if we already are in a parallel session, // then abort multi-threading // FIXME omp_get_num_threads()>1 only works for openmp, what if the user does not use openmp? if((!Condition) || (threads==1) || (omp_get_num_threads()>1)) |