Basic Vulkan Multi-GPU implementation (#5321)

* Initial Vulkan multi-gpu implementation

Move most global variables into backend context

* Add names to backend device functions

* Add further missing cleanup code

* Reduce code duplication in tensor split layer assignment

* generalize LLAMA_SPLIT_LAYER for all backends, do not expose device count and memory in llama.h

* Only do device info print in the beginning and initialize one backend for cpu assist

Add missing cleanup code

* Rework backend memory management to make sure devices and buffers get properly allocated and freed

* Rename cpu assist free function

---------

Co-authored-by: slaren <slarengh@gmail.com>

common/common.cpp

@@ -46,6 +46,10 @@
 #define GGML_USE_CUBLAS_SYCL
 #endif
 
+#if (defined(GGML_USE_CUBLAS) || defined(GGML_USE_SYCL)) || defined(GGML_USE_VULKAN)
+#define GGML_USE_CUBLAS_SYCL_VULKAN
+#endif
+
 int32_t get_num_physical_cores() {
 #ifdef __linux__
     // enumerate the set of thread siblings, num entries is num cores
@@ -660,8 +664,8 @@ bool gpt_params_parse_ex(int argc, char ** argv, gpt_params & params) {
                     params.tensor_split[i] = 0.0f;
                 }
             }
-#ifndef GGML_USE_CUBLAS_SYCL
+#ifndef GGML_USE_CUBLAS_SYCL_VULKAN
-            fprintf(stderr, "warning: llama.cpp was compiled without cuBLAS/SYCL. Setting a tensor split has no effect.\n");
+            fprintf(stderr, "warning: llama.cpp was compiled without cuBLAS/SYCL/Vulkan. Setting a tensor split has no effect.\n");
 #endif // GGML_USE_CUBLAS_SYCL
         } else if (arg == "--no-mmap") {
             params.use_mmap = false;

ggml-vulkan.h

@@ -8,24 +8,29 @@ extern "C" {
 #endif
 
 #define GGML_VK_NAME "Vulkan"
+#define GGML_VK_MAX_DEVICES 16
 
-GGML_API void ggml_vk_init(void);
+GGML_API void ggml_vk_init_cpu_assist(void);
 
-GGML_API void ggml_vk_preallocate_buffers_graph(struct ggml_tensor * node);
+GGML_API void ggml_vk_preallocate_buffers_graph_cpu_assist(struct ggml_tensor * node);
-GGML_API void ggml_vk_preallocate_buffers(void);
+GGML_API void ggml_vk_preallocate_buffers_cpu_assist(void);
-GGML_API void ggml_vk_build_graph(struct ggml_tensor * node, bool last_node);
+GGML_API void ggml_vk_build_graph_cpu_assist(struct ggml_tensor * node, bool last_node);
-GGML_API bool ggml_vk_compute_forward(struct ggml_compute_params * params, struct ggml_tensor * tensor);
+GGML_API bool ggml_vk_compute_forward_cpu_assist(struct ggml_compute_params * params, struct ggml_tensor * tensor);
 #ifdef GGML_VULKAN_CHECK_RESULTS
-void ggml_vk_check_results_1(struct ggml_compute_params * params, struct ggml_tensor * tensor);
+void ggml_vk_check_results_1_cpu_assist(struct ggml_compute_params * params, struct ggml_tensor * tensor);
 #endif
-GGML_API void ggml_vk_graph_cleanup(void);
+GGML_API void ggml_vk_graph_cleanup_cpu_assist(void);
+GGML_API void ggml_vk_free_cpu_assist(void);
 
 // backend API
-GGML_API GGML_CALL ggml_backend_t ggml_backend_vk_init(void);
+GGML_API GGML_CALL ggml_backend_t ggml_backend_vk_init(size_t dev_num);
 
 GGML_API GGML_CALL bool ggml_backend_is_vk(ggml_backend_t backend);
+GGML_API GGML_CALL int  ggml_backend_vk_get_device_count(void);
+GGML_API GGML_CALL void ggml_backend_vk_get_device_description(int device, char * description, size_t description_size);
+GGML_API GGML_CALL void ggml_backend_vk_get_device_memory(int device, size_t * free, size_t * total);
 
-GGML_API GGML_CALL ggml_backend_buffer_type_t ggml_backend_vk_buffer_type(void);
+GGML_API GGML_CALL ggml_backend_buffer_type_t ggml_backend_vk_buffer_type(size_t dev_num);
 // pinned host buffer for use with the CPU backend for faster copies between CPU and GPU
 GGML_API GGML_CALL ggml_backend_buffer_type_t ggml_backend_vk_host_buffer_type(void);
 

ggml.c

@@ -2343,7 +2343,7 @@ struct ggml_context * ggml_init(struct ggml_init_params params) {
 #elif defined(GGML_USE_CLBLAST)
         ggml_cl_init();
 #elif defined(GGML_USE_VULKAN)
-        ggml_vk_init();
+        ggml_vk_init_cpu_assist();
 #elif defined(GGML_USE_SYCL)
         ggml_init_sycl();
 #endif
@@ -14850,10 +14850,10 @@ static void ggml_compute_forward(struct ggml_compute_params * params, struct ggm
     GGML_ASSERT(tensor->src[0] == NULL || tensor->src[0]->backend == GGML_BACKEND_CPU);
     GGML_ASSERT(tensor->src[1] == NULL || tensor->src[1]->backend == GGML_BACKEND_CPU);
 #elif defined(GGML_USE_VULKAN)
-    const bool skip_cpu = ggml_vk_compute_forward(params, tensor);
+    const bool skip_cpu = ggml_vk_compute_forward_cpu_assist(params, tensor);
 #ifdef GGML_VULKAN_CHECK_RESULTS
     if (skip_cpu) {
-        ggml_vk_check_results_1(params, tensor);
+        ggml_vk_check_results_1_cpu_assist(params, tensor);
     }
 #endif
     if (skip_cpu) {
@@ -17269,12 +17269,12 @@ int ggml_graph_compute(struct ggml_cgraph * cgraph, struct ggml_cplan * cplan) {
 
 #ifdef GGML_USE_VULKAN
     for (int i = 0; i < cgraph->n_nodes; i++) {
-        ggml_vk_preallocate_buffers_graph(cgraph->nodes[i]);
+        ggml_vk_preallocate_buffers_graph_cpu_assist(cgraph->nodes[i]);
     }
-    ggml_vk_preallocate_buffers();
+    ggml_vk_preallocate_buffers_cpu_assist();
 
     for (int i = 0; i < cgraph->n_nodes; i++) {
-        ggml_vk_build_graph(cgraph->nodes[i], i == cgraph->n_nodes - 1);
+        ggml_vk_build_graph_cpu_assist(cgraph->nodes[i], i == cgraph->n_nodes - 1);
     }
 #endif
 
@@ -17330,7 +17330,7 @@ int ggml_graph_compute(struct ggml_cgraph * cgraph, struct ggml_cplan * cplan) {
     }
 
 #ifdef GGML_USE_VULKAN
-    ggml_vk_graph_cleanup();
+    ggml_vk_graph_cleanup_cpu_assist();
 #endif
 
     // performance stats (graph)

llama.cpp

@@ -1355,7 +1355,7 @@ static ggml_backend_buffer_type_t llama_default_buffer_type_offload(int gpu) {
 #elif defined(GGML_USE_CUBLAS)
     buft = ggml_backend_cuda_buffer_type(gpu);
 #elif defined(GGML_USE_VULKAN)
-    buft = ggml_backend_vk_buffer_type();
+    buft = ggml_backend_vk_buffer_type(gpu);
 #elif defined(GGML_USE_SYCL)
     buft = ggml_backend_sycl_buffer_type(gpu);
 #elif defined(GGML_USE_CLBLAST)
@@ -1392,6 +1392,33 @@ static ggml_backend_buffer_type_t llama_default_buffer_type_split(int fallback_g
     GGML_UNUSED(tensor_split);
 }
 
+static size_t llama_get_device_count() {
+#if defined(GGML_USE_CUBLAS)
+    return ggml_backend_cuda_get_device_count();
+#elif defined(GGML_USE_VULKAN)
+    return ggml_backend_vk_get_device_count();
+#else
+    return 1;
+#endif
+}
+
+static size_t llama_get_device_memory(int device) {
+#if defined(GGML_USE_CUBLAS)
+    size_t total;
+    size_t free;
+    ggml_backend_cuda_get_device_memory(device, &total, &free);
+    return free;
+#elif defined(GGML_USE_VULKAN)
+    size_t total;
+    size_t free;
+    ggml_backend_vk_get_device_memory(device, &total, &free);
+    return free;
+#else
+    return 1;
+    GGML_UNUSED(device);
+#endif
+}
+
 //
 // globals
 //
@@ -1763,6 +1790,10 @@ struct llama_context {
             ggml_backend_free(backend);
         }
 
+#ifdef GGML_USE_VULKAN
+        ggml_vk_free_cpu_assist();
+#endif
+
         ggml_backend_buffer_free(buf_input);
         ggml_free(ctx_input);
     }
@@ -3436,22 +3467,18 @@ static bool llm_load_tensors(
         model.buft_layer[i] = llama_default_buffer_type_cpu(true);
     }
 
-#ifdef GGML_USE_CUBLAS
     if (split_mode == LLAMA_SPLIT_LAYER) {
         // calculate the split points
-        int device_count = ggml_backend_cuda_get_device_count();
+        int device_count = llama_get_device_count();
         bool all_zero = tensor_split == nullptr || std::all_of(tensor_split, tensor_split + device_count, [](float x) { return x == 0.0f; });
-        float splits[GGML_CUDA_MAX_DEVICES];
+        std::vector<float> splits(device_count);
         if (all_zero) {
             // default split, by free memory
             for (int i = 0; i < device_count; ++i) {
-                size_t total;
+                splits[i] = llama_get_device_memory(i);
-                size_t free;
-                ggml_backend_cuda_get_device_memory(i, &total, &free);
-                splits[i] = free;
             }
         } else {
-            std::copy(tensor_split, tensor_split + device_count, splits);
+            std::copy(tensor_split, tensor_split + device_count, splits.begin());
         }
 
         // sum and normalize the splits to get the split points
@@ -3467,19 +3494,17 @@ static bool llm_load_tensors(
         // assign the repeating layers to the devices according to the splits
         int act_gpu_layers = std::min(n_gpu_layers, (int)n_layer + 1);
         for (int64_t i = i_gpu_start; i < n_layer; ++i) {
-            int layer_gpu = std::upper_bound(splits, splits + device_count, float(i - i_gpu_start)/act_gpu_layers) - splits;
+            int layer_gpu = std::upper_bound(splits.begin(), splits.begin() + device_count, float(i - i_gpu_start)/act_gpu_layers) - splits.begin();
             model.buft_layer[i] = llama_default_buffer_type_offload(layer_gpu);
         }
         // assign the output layer
         if (n_gpu_layers > n_layer) {
-            int layer_gpu = std::upper_bound(splits, splits + device_count, float(act_gpu_layers - 1)/act_gpu_layers) - splits;
+            int layer_gpu = std::upper_bound(splits.begin(), splits.begin() + device_count, float(act_gpu_layers - 1)/act_gpu_layers) - splits.begin();
             model.buft_output = llama_default_buffer_type_offload(layer_gpu);
         } else {
             model.buft_output = llama_default_buffer_type_cpu(true);
         }
-    } else
+    } else {
-#endif
-    {
         ggml_backend_buffer_type_t split_buft;
         if (split_mode == LLAMA_SPLIT_ROW) {
             split_buft = llama_default_buffer_type_split(main_gpu, tensor_split);
@@ -10483,6 +10508,8 @@ size_t llama_max_devices(void) {
     return GGML_CUDA_MAX_DEVICES;
 #elif defined(GGML_USE_SYCL)
     return GGML_SYCL_MAX_DEVICES;
+#elif defined(GGML_USE_VULKAN)
+    return GGML_VK_MAX_DEVICES;
 #else
     return 1;
 #endif
@@ -10690,13 +10717,15 @@ struct llama_context * llama_new_context_with_model(
         }
 #elif defined(GGML_USE_VULKAN)
         if (model->n_gpu_layers > 0) {
-            ggml_backend_t backend = ggml_backend_vk_init();
+            for (int device = 0; device < ggml_backend_vk_get_device_count(); ++device) {
-            if (backend == nullptr) {
+                ggml_backend_t backend = ggml_backend_vk_init(device);
-                LLAMA_LOG_ERROR("%s: failed to initialize Vulkan backend\n", __func__);
+                if (backend == nullptr) {
-                llama_free(ctx);
+                    LLAMA_LOG_ERROR("%s: failed to initialize Vulkan%d backend\n", __func__, device);
-                return nullptr;
+                    llama_free(ctx);
+                    return nullptr;
+                }
+                ctx->backends.push_back(backend);
             }
-            ctx->backends.push_back(backend);
         }
 #elif defined(GGML_USE_SYCL)
         if (model->n_gpu_layers > 0) {