Merge pull request #3702 from martin-frbg/issue3687

Add openblas_getaffinity() extension (Linux-only)

Author: martin-frbg

cblas.h

@@ -28,6 +28,8 @@ char* openblas_get_corename(void);
 #ifdef OPENBLAS_OS_LINUX
 /* Sets thread affinity for OpenBLAS threads. `thread_idx` is in [0, openblas_get_num_threads()-1]. */
 int openblas_setaffinity(int thread_idx, size_t cpusetsize, cpu_set_t* cpu_set);
+/* Queries thread affinity for OpenBLAS threads. `thread_idx` is in [0, openblas_get_num_threads()-1]. */
+int openblas_getaffinity(int thread_idx, size_t cpusetsize, cpu_set_t* cpu_set);
 #endif
 
 /* Get the parallelization type which is used by OpenBLAS */

driver/others/blas_server.c

@@ -352,6 +352,20 @@ int openblas_setaffinity(int thread_idx, size_t cpusetsize, cpu_set_t* cpu_set)
 
   return pthread_setaffinity_np(thread, cpusetsize, cpu_set);
 }
+int openblas_getaffinity(int thread_idx, size_t cpusetsize, cpu_set_t* cpu_set) {
+  const int active_threads = openblas_get_num_threads();
+
+  if (thread_idx < 0 || thread_idx >= active_threads) {
+    errno = EINVAL;
+    return -1;
+  }
+
+  pthread_t thread = (thread_idx == active_threads - 1)
+      ? pthread_self()
+      : blas_threads[thread_idx];
+
+  return pthread_getaffinity_np(thread, cpusetsize, cpu_set);
+}
 #endif
 
 static void* blas_thread_server(void *arg){