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Improved the blocking strategy to speedup multithreaded tensor contractions.

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This commit is contained in:
Benoit Steiner 2015-04-09 16:44:10 -07:00
parent 0eb220c00d
commit 5401fbcc50
1 changed files with 9 additions and 5 deletions
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14
Eigen/src/Core/products/GeneralBlockPanelKernel.h
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@ -112,14 +112,18 @@ void evaluateProductBlockingSizesHeuristic(Index& k, Index& m, Index& n, Index n
nr = Traits::nr,
nr_mask = (0xffffffff/nr)*nr
};
Index k_cache = (l1-ksub)/kdiv;
// Increasing k gives us more time to prefetch the content of the "C"
// registers. However once the latency is hidden there is no point in
// increasing the value of k, so we'll cap it at 320 (value determined
// experimentally).
const Index k_cache = (std::min<Index>)((l1-ksub)/kdiv, 320);
if (k_cache < k) {
k = k_cache & k_mask;
eigen_internal_assert(k > 0);
}
Index n_cache = (l2-l1) / (nr * sizeof(RhsScalar) * k);
Index n_per_thread = numext::div_ceil(n, num_threads);
const Index n_cache = (l2-l1) / (nr * sizeof(RhsScalar) * k);
const Index n_per_thread = numext::div_ceil(n, num_threads);
if (n_cache <= n_per_thread) {
// Don't exceed the capacity of the l2 cache.
eigen_internal_assert(n_cache >= static_cast<Index>(nr));
@ -131,8 +135,8 @@ void evaluateProductBlockingSizesHeuristic(Index& k, Index& m, Index& n, Index n
if (l3 > l2) {
// l3 is shared between all cores, so we'll give each thread its own chunk of l3.
Index m_cache = (l3-l2) / (sizeof(LhsScalar) * k * num_threads);
Index m_per_thread = numext::div_ceil(m, num_threads);
const Index m_cache = (l3-l2) / (sizeof(LhsScalar) * k * num_threads);
const Index m_per_thread = numext::div_ceil(m, num_threads);
if(m_cache < m_per_thread && m_cache >= static_cast<Index>(mr)) {
m = m_cache & mr_mask;
eigen_internal_assert(m > 0);