Free Cublas GPU memory

I have corrected the PR ggerganov#5576 which causes crash and streamlined the code.
Unfortunately, this does not free all occupied GPU memory yet (only 15% of it). We still need to find some objects which are not freed after releasing GPU memory.

ggml-cuda.cu

@@ -8751,10 +8751,11 @@ GGML_CALL bool ggml_cublas_loaded(void) {
     return g_cublas_loaded;
 }
 
+static bool g_cublas_initialized = false;
+
 GGML_CALL void ggml_init_cublas() {
-    static bool initialized = false;
 
-    if (!initialized) {
+    if (!g_cublas_initialized) {
 
 #ifdef __HIP_PLATFORM_AMD__
         // Workaround for a rocBLAS bug when using multiple graphics cards:
@@ -8764,7 +8765,7 @@ GGML_CALL void ggml_init_cublas() {
 #endif
 
         if (cudaGetDeviceCount(&g_device_count) != cudaSuccess) {
-            initialized = true;
+            g_cublas_initialized = true;
             g_cublas_loaded = false;
             fprintf(stderr, "%s: no " GGML_CUDA_NAME " devices found, " GGML_CUDA_NAME " will be disabled\n", __func__);
             return;
@@ -8835,7 +8836,7 @@ GGML_CALL void ggml_init_cublas() {
         // configure logging to stdout
         // CUBLAS_CHECK(cublasLoggerConfigure(1, 1, 0, nullptr));
 
-        initialized = true;
+        g_cublas_initialized = true;
         g_cublas_loaded = true;
     }
 }
@@ -12490,3 +12491,15 @@ GGML_CALL int ggml_backend_cuda_reg_devices() {
     }
     return device_count;
 }
+
+extern "C" GGML_CALL void ggml_free_cublas(void);
+
+GGML_CALL void ggml_free_cublas(void) {
+#ifdef GGML_USE_CUBLAS
+    for (int id = 0; id < g_device_count; ++id) {
+        CUBLAS_CHECK(cublasDestroy(g_cublas_handles[id]));
+        g_cublas_handles[id] = nullptr;
+    }
+    g_cublas_initialized = false;
+#endif
+}

ggml-cuda.h

@@ -17,6 +17,9 @@ extern "C" {
 
 #define GGML_CUDA_MAX_DEVICES       16
 
+// Release CUDA resources
+GGML_API GGML_CALL void   ggml_free_cublas(void);
+
 // Always success. To check if CUDA is actually loaded, use `ggml_cublas_loaded`.
 GGML_API GGML_CALL void   ggml_init_cublas(void);