solve: introduce a trivial preconditioner

buildme

@@ -0,0 +1 @@
+cd build && make -j16

opm/simulators/linalg/StandardPreconditioners_serial.hpp

@@ -31,6 +31,19 @@
 
 namespace Opm {
 
+template <class X, class Y>
+class TrivialPreconditioner : public Dune::PreconditionerWithUpdate<X, Y>
+{
+    public:
+    TrivialPreconditioner(){};
+    virtual void update() override {};
+    virtual bool hasPerfectUpdate() const override {return true;}
+    virtual void pre (X& x, Y& y) override {};
+    virtual void post (X& x) override {};
+    virtual void apply (X& x, const Y& y) override {};
+    virtual Dune::SolverCategory::Category category() const override { return Dune::SolverCategory::sequential; };
+};
+
 
 template <class Operator>
 struct StandardPreconditioners<Operator, Dune::Amg::SequentialInformation, typename std::enable_if_t<!Opm::is_gpu_operator_v<Operator>>>
@@ -71,6 +84,14 @@ struct StandardPreconditioners<Operator, Dune::Amg::SequentialInformation, typen
             DUNE_UNUSED_PARAMETER(prm);
             return std::make_shared<MultithreadDILU<M, V, V>>(op.getmat());
         });
+        F::addCreator("mixed-ilu0", [](const O& op, const P& prm, const std::function<V()>&, std::size_t) {
+            DUNE_UNUSED_PARAMETER(prm);
+            return std::make_shared<TrivialPreconditioner<V,V>>();
+        });
+        F::addCreator("mixed-dilu", [](const O& op, const P& prm, const std::function<V()>&, std::size_t) {
+            DUNE_UNUSED_PARAMETER(prm);
+            return std::make_shared<TrivialPreconditioner<V,V>>();
+        });
         F::addCreator("jac", [](const O& op, const P& prm, const std::function<V()>&, std::size_t) {
             const int n = prm.get<int>("repeats", 1);
             const double w = prm.get<double>("relaxation", 1.0);

opm/simulators/linalg/setupPropertyTree.cpp

@@ -408,6 +408,7 @@ setupMixedILU([[maybe_unused]] const std::string& conf, const FlowLinearSolverPa
     prm.put("maxiter", p.linear_solver_maxiter_);
     prm.put("verbosity", p.linear_solver_verbosity_);
     prm.put("solver", "mixed-bicgstab"s);
+    prm.put("preconditioner.type", "trivial"s);
     return prm;
 }
 

shellme

@@ -0,0 +1 @@
+guix shell -L ~/repos/nrseman/aaguix --share=$PWD/.. -CD opm-simulators