Barrier method for LPs with cuDSS sparse Cholesky / LDLT on the GPU (#272)

This PR adds a barrier (interior-point) method for solving linear programs. cuDSS is used to GPU-accelerate the sparse Cholesky and sparse LDLT solves, cuSparse is used to GPU-accelerate spMv and spMM.  This PR also includes routines for the color refinement algorithm (generalized to weighted graphs) and folding a linear program. Crossover is also updated to use hypersparse solves. 

Barrier is enabled by default (along with PDLP and dual simplex) in concurrent mode. You may also use barrier by itself.

The following new settings are supported:
*  `--method=3` to invoke the new barrier solver
*  `--folding`   to control whether to fold the LP: (-1) automatic, (0) folding off, (1) folding in
*  `--dualize` to control whether to dualize the LP in presolve: (-1) automatic, (0) don't dualize, (1) force dualize
*  `--ordering` to control whether the ordering for cuDSS: (-1) automatic, (0) cuDSS default (1) AMD
*  `--augmented` to control what linear system to solve:  (-1) automatic, (0) solve ADAT, (1) solve the augmented system 
*  `--eliminate-dense-columns`, true to eliminate dense columns, false to not
*  `--cudss-deterministic`, true to use cuDSS deterministic mode, false to use nondeterministic mode


Closes #204

Authors:
  - Chris Maes (https://github.com/chris-maes)
  - Nicolas Blin (https://github.com/Kh4ster)
  - Hugo Linsenmaier (https://github.com/hlinsen)
  - Ramakrishnap (https://github.com/rgsl888prabhu)
  - Ishika Roy (https://github.com/Iroy30)
  - Rajesh Gandham (https://github.com/rg20)

Approvers:
  - Trevor McKay (https://github.com/tmckayus)
  - Hugo Linsenmaier (https://github.com/hlinsen)
  - Bradley Dice (https://github.com/bdice)

URL: #272

Author: chris-maes

benchmarks/linear_programming/cuopt/run_pdlp.cu

@@ -63,10 +63,10 @@ static void parse_arguments(argparse::ArgumentParser& program)
   program.add_argument("--method")
     .help(
       "Method to solve the linear programming problem. 0: Concurrent (default), 1: PDLP, 2: "
-      "DualSimplex")
+      "DualSimplex, 3: Barrier")
     .default_value(0)
     .scan<'i', int>()
-    .choices(0, 1, 2);
+    .choices(0, 1, 2, 3);
 
   program.add_argument("--crossover")
     .help("Enable crossover. 0: disabled (default), 1: enabled")
@@ -79,6 +79,12 @@ static void parse_arguments(argparse::ArgumentParser& program)
       "Path to PDLP hyper-params file to configure PDLP solver. Has priority over PDLP solver "
       "modes.");
 
+  program.add_argument("--presolve")
+    .help("enable/disable presolve (default: true for MIP problems, false for LP problems)")
+    .default_value(0)
+    .scan<'i', int>()
+    .choices(0, 1);
+
   program.add_argument("--solution-path").help("Path where solution file will be generated");
 }
 
@@ -109,6 +115,7 @@ static cuopt::linear_programming::pdlp_solver_settings_t<int, double> create_sol
     string_to_pdlp_solver_mode(program.get<std::string>("--pdlp-solver-mode"));
   settings.method = static_cast<cuopt::linear_programming::method_t>(program.get<int>("--method"));
   settings.crossover = program.get<int>("--crossover");
+  settings.presolve  = program.get<int>("--presolve");
 
   return settings;
 }

ci/build_wheel_cuopt.sh

@@ -20,6 +20,14 @@ set -euo pipefail
 
 source rapids-init-pip
 
+# Install rockylinux repo
+if command -v dnf &> /dev/null; then
+    bash ci/utils/update_rockylinux_repo.sh
+fi
+
+# Install cudss
+bash ci/utils/install_cudss.sh
+
 package_dir="python/cuopt"
 export SKBUILD_CMAKE_ARGS="-DCUOPT_BUILD_WHEELS=ON;-DDISABLE_DEPRECATION_WARNINGS=ON";
 
@@ -41,6 +49,8 @@ EXCLUDE_ARGS=(
   --exclude "libraft.so"
   --exclude "libcublas.so.*"
   --exclude "libcublasLt.so.*"
+  --exclude "libcuda.so.1"
+  --exclude "libcudss.so.*"
   --exclude "libcurand.so.*"
   --exclude "libcusolver.so.*"
   --exclude "libcusparse.so.*"

ci/build_wheel_libcuopt.sh

@@ -21,6 +21,11 @@ source rapids-init-pip
 package_name="libcuopt"
 package_dir="python/libcuopt"
 
+# Install rockylinux repo
+if command -v dnf &> /dev/null; then
+    bash ci/utils/update_rockylinux_repo.sh
+fi
+
 # Install Boost and TBB
 bash ci/utils/install_boost_tbb.sh
 
@@ -34,6 +39,9 @@ else
     echo "Building in release mode"
 fi
 
+# Install cudss
+bash ci/utils/install_cudss.sh
+
 rapids-logger "Generating build requirements"
 
 CUOPT_MPS_PARSER_WHEELHOUSE=$(RAPIDS_PY_WHEEL_NAME="cuopt_mps_parser" rapids-download-wheels-from-github python)
@@ -62,6 +70,8 @@ EXCLUDE_ARGS=(
   --exclude "libraft.so"
   --exclude "libcublas.so.*"
   --exclude "libcublasLt.so.*"
+  --exclude "libcuda.so.1"
+  --exclude "libcudss.so.*"
   --exclude "libcurand.so.*"
   --exclude "libcusolver.so.*"
   --exclude "libcusparse.so.*"

ci/utils/install_boost_tbb.sh

@@ -22,8 +22,6 @@ if [ -f /etc/os-release ]; then
     . /etc/os-release
     if [[ "$ID" == "rocky" ]]; then
         echo "Detected Rocky Linux. Installing Boost and TBB via dnf..."
-        dnf clean all
-        dnf -y update
         dnf install -y epel-release
         dnf install -y boost1.78-devel tbb-devel
         if [[ "$(uname -m)" == "x86_64" ]]; then

ci/utils/install_cudss.sh

@@ -0,0 +1,34 @@
+#!/bin/bash
+
+# SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -euo pipefail
+
+# Clean metadata & install cudss
+if command -v dnf &> /dev/null; then
+    # Adding static library just to please CMAKE requirements
+    if [ "$(echo "$CUDA_VERSION" | cut -d. -f1)" -ge 13 ] && [ "$(echo "$CUDA_VERSION" | cut -d. -f1)" -lt 14 ]; then
+        dnf -y install libcudss0-static-cuda-13 libcudss0-devel-cuda-13 libcudss0-cuda-13
+    else
+        dnf -y install libcudss0-static-cuda-12 libcudss0-devel-cuda-12 libcudss0-cuda-12
+    fi
+elif command -v apt-get &> /dev/null; then
+    apt-get update
+    apt-get install -y libcudss-devel
+else
+    echo "Neither dnf nor apt-get found. Cannot install cudss dependencies."
+    exit 1
+fi

ci/utils/update_rockylinux_repo.sh

@@ -0,0 +1,88 @@
+#!/bin/bash
+
+# SPDX-FileCopyrightText: Copyright (c) 2025, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -euo pipefail
+
+REPO_DIR="/etc/yum.repos.d"
+
+# Disable all existing Rocky repos to prevent mirror issues
+for repo_file in ${REPO_DIR}/Rocky-*.repo; do
+    if [ -f "$repo_file" ]; then
+        sed -i 's/^enabled=1/enabled=0/g' "$repo_file"
+    fi
+done
+
+# Overwrite the main Rocky repos with stable URLs
+# Using ONLY direct dl.rockylinux.org URLs (no mirrorlist) to avoid mirror sync issues
+# This prevents DNF from trying unreliable/out-of-sync mirrors
+cat <<'EOF' > ${REPO_DIR}/Rocky-BaseOS.repo
+[baseos]
+name=Rocky Linux 8.10 - BaseOS
+baseurl=https://dl.rockylinux.org/pub/rocky/8.10/BaseOS/$basearch/os/
+enabled=1
+gpgcheck=1
+gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-rockyofficial
+retries=10
+timeout=30
+skip_if_unavailable=False
+metadata_expire=1h
+EOF
+
+cat <<'EOF' > ${REPO_DIR}/Rocky-AppStream.repo
+[appstream]
+name=Rocky Linux 8.10 - AppStream
+baseurl=https://dl.rockylinux.org/pub/rocky/8.10/AppStream/$basearch/os/
+enabled=1
+gpgcheck=1
+gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-rockyofficial
+retries=10
+timeout=30
+skip_if_unavailable=False
+metadata_expire=1h
+EOF
+
+cat <<'EOF' > ${REPO_DIR}/Rocky-Extras.repo
+[extras]
+name=Rocky Linux 8.10 - Extras
+baseurl=https://dl.rockylinux.org/pub/rocky/8.10/extras/$basearch/os/
+enabled=1
+gpgcheck=1
+gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-rockyofficial
+retries=10
+timeout=30
+skip_if_unavailable=False
+metadata_expire=1h
+EOF
+
+# Clean DNF cache and refresh repository metadata with retry logic
+dnf clean all
+
+max_attempts=3
+attempt=1
+while [ $attempt -le $max_attempts ]; do
+    if dnf makecache --refresh; then
+        break
+    else
+        if [ $attempt -lt $max_attempts ]; then
+            sleep $((2 ** attempt))
+        else
+            echo "ERROR: Failed to refresh repository metadata after $max_attempts attempts"
+            exit 1
+        fi
+    fi
+    attempt=$((attempt + 1))
+done

conda/environments/all_cuda-129_arch-aarch64.yaml

@@ -32,6 +32,7 @@ dependencies:
 - gtest
 - ipython
 - jsonref==1.1.0
+- libcudss-dev >=0.7
 - libcurand-dev
 - libcusolver-dev
 - libcusparse-dev

conda/environments/all_cuda-129_arch-x86_64.yaml

@@ -32,6 +32,7 @@ dependencies:
 - gtest
 - ipython
 - jsonref==1.1.0
+- libcudss-dev >=0.7
 - libcurand-dev
 - libcusolver-dev
 - libcusparse-dev

conda/environments/all_cuda-130_arch-aarch64.yaml

@@ -32,6 +32,7 @@ dependencies:
 - gtest
 - ipython
 - jsonref==1.1.0
+- libcudss-dev >=0.7
 - libcurand-dev
 - libcusolver-dev
 - libcusparse-dev

conda/environments/all_cuda-130_arch-x86_64.yaml

@@ -32,6 +32,7 @@ dependencies:
 - gtest
 - ipython
 - jsonref==1.1.0
+- libcudss-dev >=0.7
 - libcurand-dev
 - libcusolver-dev
 - libcusparse-dev