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slightly optimize computeProductBlockingSizes by explicitely precomputing what is known at compile time

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This commit is contained in:
Gael Guennebaud
2010-06-22 11:10:38 +02:00
parent 3ae0eee0b8
commit fd9a9fa0ae
2 changed files with 18 additions and 9 deletions
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17
Eigen/src/Core/products/GeneralBlockPanelKernel.h
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@@ -93,7 +93,7 @@ inline void setCpuCacheSizes(std::ptrdiff_t l1, std::ptrdiff_t l2)
* \param[in,out] n Input: the number of columns of the right hand side. Output: the blocking size along the same dimension.
*
* Given a m x k times k x n matrix product of scalar types \c LhsScalar and \c RhsScalar,
* this function computes the blocking size parameters along the respective dimensions
* this function computes the blocking size parameters along the respective dimensions
* for matrix products and related algorithms. The blocking sizes depends on various
* parameters:
* - the L1 and L2 cache sizes,
@@ -112,11 +112,18 @@ void computeProductBlockingSizes(std::ptrdiff_t& k, std::ptrdiff_t& m, std::ptrd
// i.e., each coefficient is replicated to fit a packet. This small vertical panel has to
// stay in L1 cache.
std::ptrdiff_t l1, l2;
enum {
kdiv = 2 * ei_product_blocking_traits<RhsScalar>::nr
* ei_packet_traits<RhsScalar>::size * sizeof(RhsScalar),
mr = ei_product_blocking_traits<LhsScalar>::mr,
mr_mask = (0xffffffff/mr)*mr
};
ei_manage_caching_sizes(GetAction, &l1, &l2);
k = std::min<std::ptrdiff_t>(k, l1/(2 * ei_product_blocking_traits<RhsScalar>::nr
* ei_packet_traits<RhsScalar>::size * sizeof(RhsScalar)));
std::ptrdiff_t _m = l2/(4 * k * sizeof(LhsScalar));
if(_m<m) m = (_m/ei_product_blocking_traits<LhsScalar>::mr) * ei_product_blocking_traits<LhsScalar>::mr;
k = std::min<std::ptrdiff_t>(k, l1/kdiv);
std::ptrdiff_t _m = l2/(4 * sizeof(LhsScalar) * k);
if(_m<m) m = _m & mr_mask;
n = n;
}