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Improve blocking heuristic: if the lhs fit within L1, then block on the rhs in L1 (allows to keep packed rhs in L1)

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Gael Guennebaud 2015-03-06 14:31:39 +01:00
parent eedd5063fd
commit cd3bbffa73
1 changed files with 16 additions and 2 deletions
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18
Eigen/src/Core/products/GeneralBlockPanelKernel.h
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@ -213,8 +213,22 @@ void computeProductBlockingSizes(Index& k, Index& m, Index& n, Index num_threads
// Here, nc is chosen such that a block of kc x nc of the rhs fit within half of L2.
// The second half is implicitly reserved to access the result and lhs coefficients.
// When k<max_kc, then nc can arbitrarily growth. In practice, it seems to be fruitful
// to limit this growth: we bound nc to growth by a factor x1.5, leading to:
const Index max_nc = (3*actual_l2)/(2*2*max_kc*sizeof(RhsScalar));
// to limit this growth: we bound nc to growth by a factor x1.5.
// However, if the entire lhs block fit within L1, then we are not going to block on the rows at all,
// and it becomes fruitful to keep the packed rhs blocks in L1 if there is enough remaining space.
Index max_nc;
const Index lhs_bytes = m * k * sizeof(LhsScalar);
const Index remaining_l1 = l1- k_sub - lhs_bytes;
if(remaining_l1 >= Index(Traits::nr*sizeof(RhsScalar))*k)
{
// L1 blocking
max_nc = remaining_l1 / (k*sizeof(RhsScalar));
}
else
{
// L2 blocking
max_nc = (3*actual_l2)/(2*2*max_kc*sizeof(RhsScalar));
}
// WARNING Below, we assume that Traits::nr is a power of two.
Index nc = std::min<Index>(actual_l2/(2*k*sizeof(RhsScalar)), max_nc) & (~(Traits::nr-1));
if(n>nc)