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Performance tweak for dual_simplex/right_looking_lu #315

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Merged
rapids-bot merged 6 commits into from
Aug 26, 2025
Merged

Performance tweak for dual_simplex/right_looking_lu #315

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41976b3
Performance tweak for dual_simplex/right_looking_lu
ahehn-nv Aug 18, 2025
0991429
Merge branch 'branch-25.10' into ahehn/right_looking_lu_fix
rgsl888prabhu Aug 18, 2025
bc2f970
Merge branch 'branch-25.10' into ahehn/right_looking_lu_fix
ahehn-nv Aug 21, 2025
501804d
Merge branch 'branch-25.10' into ahehn/right_looking_lu_fix
chris-maes Aug 22, 2025
686ae64
Merge branch 'branch-25.10' into ahehn/right_looking_lu_fix
ahehn-nv Aug 25, 2025
7b90bb1
Merge branch 'branch-25.10' into ahehn/right_looking_lu_fix
rgsl888prabhu Aug 26, 2025
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49 changes: 28 additions & 21 deletions cpp/src/dual_simplex/right_looking_lu.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,6 @@
#include <cassert>
#include <cmath>
#include <cstdio>
#include <list>

namespace cuopt::linear_programming::dual_simplex {

Expand All @@ -44,8 +43,8 @@ i_t initialize_degree_data(const csc_matrix_t<i_t, f_t>& A,
const std::vector<i_t>& column_list,
std::vector<i_t>& Cdegree,
std::vector<i_t>& Rdegree,
std::vector<std::list<i_t>>& col_count,
std::vector<std::list<i_t>>& row_count)
std::vector<std::vector<i_t>>& col_count,
std::vector<std::vector<i_t>>& row_count)
{
const i_t n = column_list.size();
const i_t m = A.m;
Expand Down Expand Up @@ -195,8 +194,8 @@ void initialize_max_in_row(const std::vector<i_t>& first_in_row,
template <typename i_t, typename f_t>
i_t markowitz_search(const std::vector<i_t>& Cdegree,
const std::vector<i_t>& Rdegree,
const std::vector<std::list<i_t>>& col_count,
const std::vector<std::list<i_t>>& row_count,
const std::vector<std::vector<i_t>>& col_count,
const std::vector<std::vector<i_t>>& row_count,
const std::vector<i_t>& first_in_row,
const std::vector<i_t>& first_in_col,
const std::vector<f_t>& max_in_column,
Expand Down Expand Up @@ -306,7 +305,7 @@ void update_Cdegree_and_col_count(i_t pivot_i,
i_t pivot_j,
const std::vector<i_t>& first_in_row,
std::vector<i_t>& Cdegree,
std::vector<std::list<i_t>>& col_count,
std::vector<std::vector<i_t>>& col_count,
std::vector<element_t<i_t, f_t>>& elements)
{
// Update Cdegree and col_count
Expand All @@ -316,11 +315,13 @@ void update_Cdegree_and_col_count(i_t pivot_i,
assert(entry->i == pivot_i);
i_t cdeg = Cdegree[j];
assert(cdeg >= 0);
for (typename std::list<i_t>::iterator it = col_count[cdeg].begin();
for (typename std::vector<i_t>::iterator it = col_count[cdeg].begin();
it != col_count[cdeg].end();
it++) {
if (*it == j) {
col_count[cdeg].erase(it);
// Remove col j from col_count[cdeg]
std::swap(*it, col_count[cdeg].back());
col_count[cdeg].pop_back();
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break;
}
}
Expand All @@ -336,7 +337,7 @@ void update_Rdegree_and_row_count(i_t pivot_i,
i_t pivot_j,
const std::vector<i_t>& first_in_col,
std::vector<i_t>& Rdegree,
std::vector<std::list<i_t>>& row_count,
std::vector<std::vector<i_t>>& row_count,
std::vector<element_t<i_t, f_t>>& elements)
{
// Update Rdegree and row_count
Expand All @@ -345,11 +346,13 @@ void update_Rdegree_and_row_count(i_t pivot_i,
const i_t i = entry->i;
i_t rdeg = Rdegree[i];
assert(rdeg >= 0);
for (typename std::list<i_t>::iterator it = row_count[rdeg].begin();
for (typename std::vector<i_t>::iterator it = row_count[rdeg].begin();
it != row_count[rdeg].end();
it++) {
if (*it == i) {
row_count[rdeg].erase(it);
// Remove row i from row_count[rdeg]
std::swap(*it, row_count[rdeg].back());
row_count[rdeg].pop_back();
break;
}
}
Expand All @@ -375,8 +378,8 @@ void schur_complement(i_t pivot_i,
std::vector<f_t>& max_in_row,
std::vector<i_t>& Rdegree,
std::vector<i_t>& Cdegree,
std::vector<std::list<i_t>>& row_count,
std::vector<std::list<i_t>>& col_count,
std::vector<std::vector<i_t>>& row_count,
std::vector<std::vector<i_t>>& col_count,
std::vector<element_t<i_t, f_t>>& elements)
{
for (i_t p1 = first_in_col[pivot_j]; p1 != kNone; p1 = elements[p1].next_in_column) {
Expand Down Expand Up @@ -452,23 +455,27 @@ void schur_complement(i_t pivot_i,
}
row_last_workspace[i] = fill_p;
i_t rdeg = Rdegree[i]; // Rdgree must increase
for (typename std::list<i_t>::iterator it = row_count[rdeg].begin();
for (typename std::vector<i_t>::iterator it = row_count[rdeg].begin();
it != row_count[rdeg].end();
it++) {
if (*it == i) {
row_count[rdeg].erase(it); // Remove row i from row_count[rdeg]
// Remove row i from row_count[rdeg]
std::swap(*it, row_count[rdeg].back());
row_count[rdeg].pop_back();
break;
}
}
rdeg = ++Rdegree[i]; // Increase rdeg
row_count[rdeg].push_back(i); // Add row i to row_count[rdeg]

i_t cdeg = Cdegree[j]; // Cdegree must increase
for (typename std::list<i_t>::iterator it = col_count[cdeg].begin();
for (typename std::vector<i_t>::iterator it = col_count[cdeg].begin();
it != col_count[cdeg].end();
it++) {
if (*it == j) {
col_count[cdeg].erase(it); // Remove column j from col_count[cdeg]
// Remove col j from col_count[cdeg]
std::swap(*it, col_count[cdeg].back());
col_count[cdeg].pop_back();
break;
}
}
Expand Down Expand Up @@ -593,9 +600,9 @@ i_t right_looking_lu(const csc_matrix_t<i_t, f_t>& A,
std::vector<i_t> Rdegree(n); // Rdegree[i] is the degree of row i
std::vector<i_t> Cdegree(n); // Cdegree[j] is the degree of column j

std::vector<std::list<i_t>> col_count(
std::vector<std::vector<i_t>> col_count(
n + 1); // col_count[nz] is a list of columns with nz nonzeros in the active submatrix
std::vector<std::list<i_t>> row_count(
std::vector<std::vector<i_t>> row_count(
n + 1); // row_count[nz] is a list of rows with nz nonzeros in the active submatrix

const i_t Bnz = initialize_degree_data(A, column_list, Cdegree, Rdegree, col_count, row_count);
Expand Down Expand Up @@ -931,9 +938,9 @@ i_t right_looking_lu_row_permutation_only(const csc_matrix_t<i_t, f_t>& A,
std::vector<i_t> Rdegree(m); // Rdegree[i] is the degree of row i
std::vector<i_t> Cdegree(n); // Cdegree[j] is the degree of column j

std::vector<std::list<i_t>> col_count(
std::vector<std::vector<i_t>> col_count(
m + 1); // col_count[nz] is a list of columns with nz nonzeros in the active submatrix
std::vector<std::list<i_t>> row_count(
std::vector<std::vector<i_t>> row_count(
n + 1); // row_count[nz] is a list of rows with nz nonzeros in the active submatrix

std::vector<i_t> column_list(n);
Expand Down