Single-Node Mode

Replaceability

Currently, KML_SOLVER supports multiple threads on a single node and cannot replace the multi-node function of PETSc.

Table 1 describes the mapping between replaceable interfaces and corresponding interfaces of PETSc (only optimized interfaces are provided).

The preceding interfaces are C interfaces. For details, see "Kunpeng Math Library Developer Guide" > "Applied Math Libraries" > "KML_SOLVER Library Functions" > "Function Syntax (Single-node Edition)" in Kunpeng HPCKit 26.1.RC1 Developer Guide.

Migrating the C-based Library

Both PETSc and KML_SOLVER provide C interfaces. However, the interface names and receiving parameters are inconsistent. Therefore, the corresponding function needs to be switched. The following is an example:

1. Initialization
   Before the migration:

   1 2 3 4

   KSP ksp; PetscErrorCode ierr; ierr = KSPCreate(PETSC_COMM_WORLD,&ksp); ierr = KSPSetOperators(ksp,A,A);

   After the migration:

   1 2 3 4 5 6

   int n = 8; int ia[9]; int ja[17]; double a[17]; void* handle; int error = KmlIssCgInitDI(&handle, &n, a, ja, ia);

2. Finding the solution
   Before the migration:

   1 2 3 4 5 6 7 8

   Vec u,x,b; ierr = VecCreate(PETSC_COMM_WORLD,&u); ierr = VecSetSizes(u,PETSC_DECIDE,rdim); ierr = VecSetFromOptions(u);CHKERRQ(ierr); ierr = VecDuplicate(u,&b);CHKERRQ(ierr); ierr = VecDuplicate(b,&x);CHKERRQ(ierr); ierr = KSPSolve(ksp,b,x);CHKERRQ(ierr);

   After the migration:

   1 2 3 4 5 6

   double b[8]; /* Solution vector */ double x[8]; int nrhs = 1; /* Number of right-hand sides */ int ldx=n, ldb=n; /* Leading dimension of B and X */ int error = KmlIssCgSolveDI(&handle, &nrhs, x, &ldx, b, &ldb);

3. Obtaining iteration parameters
   Before the migration:

   1 2	PetscInt its; ierr = KSPGetIterationNumber(ksp,&its);CHKERRQ(ierr);

   After the migration:

   1 2 3

   int *data; // user data. int nd = 1; int error = KmlIssCgGetDII(&handle, ITERATION_COUNT, data, nd);

4. Clearing
   Before the migration:

   1	ierr = KSPDestroy(&ksp);

   After the migration:

   1	int error = KmlIssCgCleanDI(&handle);

5. Header files

   Before the migration:

   #include "petscksp.h"

   After the migration:

   #include "kml_iss.h"

6. Compiling the links

   Replace the PETSc-related link options. For details, see "Installing KML" in Kunpeng HPCKit 26.1.RC1 Installation Guide.