allow to check if Kokkos is active and retrieve number of threads and gpus

src/library.cpp

@@ -983,7 +983,7 @@ be called without a valid LAMMPS object handle (it is ignored).
 **Image masks**
 
 These settings are related to how LAMMPS stores and interprets periodic images. The values are used
-internally by the Fortran interface and are not likely to be useful to users.
+internally by the :doc:`Fortran interface <Fortran>` and are not likely to be useful to users.
 
 .. list-table::
    :header-rows: 1
@@ -1015,8 +1015,17 @@ internally by the Fortran interface and are not likely to be useful to users.
    * - box_exist
      - 1 if the simulation box is defined, 0 if not.
        See :doc:`create_box`.
+   * - kokkos_active
+     - 1 if the KOKKOS package is compiled in **and** activated, 0 if not.
+       See :doc:`<Speed_kokkos>`.
+   * - kokkos_nthreads
+     - Number of Kokkos threads per MPI process, 0 if Kokkos is not active.
+       See :doc:`<Speed_kokkos>`.
+   * - kokkos_ngpus
+     - Number of Kokkos gpus per MPI process, 0 if Kokkos is not active or no GPU support.
+       See :doc:`<Speed_kokkos>`.
    * - nthreads
-     - Number of requested OpenMP threads for LAMMPS' execution
+     - Number of requested OpenMP threads per MPI process for LAMMPS' execution
    * - newton_bond
      - 1 if Newton's 3rd law is applied to bonded interactions, 0 if not.
    * - newton_pair
@@ -1126,6 +1135,9 @@ int lammps_extract_setting(void *handle, const char *keyword)
 
   if (strcmp(keyword,"dimension") == 0) return lmp->domain->dimension;
   if (strcmp(keyword,"box_exist") == 0) return lmp->domain->box_exist;
+  if (strcmp(keyword,"kokkos_active") == 0) return (lmp->kokkos) ? 1 : 0;
+  if (strcmp(keyword,"kokkos_nthreads") == 0) return (lmp->kokkos) ? lmp->kokkos->nthreads : 0;
+  if (strcmp(keyword,"kokkos_ngpus") == 0) return (lmp->kokkos) ? lmp->kokkos->ngpus : 0;
   if (strcmp(keyword,"newton_bond") == 0) return lmp->force->newton_bond;
   if (strcmp(keyword,"newton_pair") == 0) return lmp->force->newton_pair;
   if (strcmp(keyword,"triclinic") == 0) return lmp->domain->triclinic;

unittest/c-library/test_library_properties.cpp

@@ -209,6 +209,10 @@ TEST_F(LibraryProperties, setting)
     lammps_command(lmp, "dimension 3");
     if (!verbose) ::testing::internal::GetCapturedStdout();
 
+    EXPECT_EQ(lammps_extract_setting(lmp, "kokkos_active"), 0);
+    EXPECT_EQ(lammps_extract_setting(lmp, "kokkos_nthreads"), 0);
+    EXPECT_EQ(lammps_extract_setting(lmp, "kokkos_ngpus"), 0);
+
     EXPECT_EQ(lammps_extract_setting(lmp, "world_size"), 1);
     EXPECT_EQ(lammps_extract_setting(lmp, "world_rank"), 0);
     EXPECT_EQ(lammps_extract_setting(lmp, "universe_size"), 1);
@@ -545,3 +549,27 @@ TEST_F(AtomProperties, position)
     EXPECT_DOUBLE_EQ(x[1][1], 0.1);
     EXPECT_DOUBLE_EQ(x[1][2], 0.1);
 }
+
+TEST(SystemSettings, kokkos)
+{
+    if (!lammps_config_has_package("KOKKOS")) GTEST_SKIP();
+    if (!lammps_config_accelerator("KOKKOS", "api", "openmp")) GTEST_SKIP();
+
+    // clang-format off
+    const char *args[] = {"SystemSettings", "-log", "none", "-echo", "screen", "-nocite",
+                          "-k", "on", "t", "4", "-sf", "kk"};
+    // clang-format on
+    char **argv = (char **)args;
+    int argc    = sizeof(args) / sizeof(char *);
+
+    ::testing::internal::CaptureStdout();
+    void *lmp          = lammps_open_no_mpi(argc, argv, nullptr);
+    std::string output = ::testing::internal::GetCapturedStdout();
+    if (verbose) std::cout << output;
+    EXPECT_THAT(output, StartsWith("LAMMPS ("));
+
+    EXPECT_EQ(lammps_extract_setting(lmp, "kokkos_active"), 1);
+    EXPECT_EQ(lammps_extract_setting(lmp, "kokkos_nthreads"), 4);
+    EXPECT_EQ(lammps_extract_setting(lmp, "kokkos_ngpus"), 0);    
+    lammps_close(lmp);
+}