ggml-backend : add GGML_BACKEND_DEVICE_TYPE_IGPU device type (#15797)

slaren · web-flow · commit 360d6533db39 · 2025-09-11T22:47:38.000+02:00
* ggml-backend : add GGML_BACKEND_DEVICE_TYPE_IGPU device type

ggml-backend : add device id to device props

llama : only use iGPU devices if there are no GPU devices

llama : do not use multiple devices from different backends with the same device id
diff --git a/ggml/include/ggml-backend.h b/ggml/include/ggml-backend.h
@@ -132,6 +132,8 @@ extern "C" {
         GGML_BACKEND_DEVICE_TYPE_CPU,
         // GPU device using dedicated memory
         GGML_BACKEND_DEVICE_TYPE_GPU,
+        // integrated GPU device using host memory
+        GGML_BACKEND_DEVICE_TYPE_IGPU,
         // accelerator devices intended to be used together with the CPU backend (e.g. BLAS or AMX)
         GGML_BACKEND_DEVICE_TYPE_ACCEL
     };
@@ -150,11 +152,21 @@ extern "C" {
 
     // all the device properties
     struct ggml_backend_dev_props {
+        // device name
         const char * name;
+        // device description
         const char * description;
+        // device free memory in bytes
         size_t memory_free;
+        // device total memory in bytes
         size_t memory_total;
+        // device type
         enum ggml_backend_dev_type type;
+        // device id
+        //   for PCI devices, this should be the PCI bus id formatted as "domain:bus:device.function" (e.g. "0000:01:00.0")
+        //   if the id is unknown, this should be NULL
+        const char * device_id;
+        // device capabilities
         struct ggml_backend_dev_caps caps;
     };
 
diff --git a/ggml/src/ggml-backend-impl.h b/ggml/src/ggml-backend-impl.h
@@ -8,7 +8,7 @@
 extern "C" {
 #endif
 
-    #define GGML_BACKEND_API_VERSION 1
+    #define GGML_BACKEND_API_VERSION 2
 
     //
     // Backend buffer type
diff --git a/ggml/src/ggml-backend-reg.cpp b/ggml/src/ggml-backend-reg.cpp
@@ -400,9 +400,8 @@ ggml_backend_t ggml_backend_init_by_type(enum ggml_backend_dev_type type, const
 
 ggml_backend_t ggml_backend_init_best(void) {
     ggml_backend_dev_t dev = ggml_backend_dev_by_type(GGML_BACKEND_DEVICE_TYPE_GPU);
-    if (!dev) {
-        dev = ggml_backend_dev_by_type(GGML_BACKEND_DEVICE_TYPE_CPU);
-    }
+    dev = dev ? dev : ggml_backend_dev_by_type(GGML_BACKEND_DEVICE_TYPE_IGPU);
+    dev = dev ? dev : ggml_backend_dev_by_type(GGML_BACKEND_DEVICE_TYPE_CPU);
     if (!dev) {
         return nullptr;
     }
diff --git a/ggml/src/ggml-cuda/ggml-cuda.cu b/ggml/src/ggml-cuda/ggml-cuda.cu
@@ -3210,6 +3210,7 @@ struct ggml_backend_cuda_device_context {
     int device;
     std::string name;
     std::string description;
+    std::string pci_bus_id;
 };
 
 static const char * ggml_backend_cuda_device_get_name(ggml_backend_dev_t dev) {
@@ -3234,9 +3235,12 @@ static enum ggml_backend_dev_type ggml_backend_cuda_device_get_type(ggml_backend
 }
 
 static void ggml_backend_cuda_device_get_props(ggml_backend_dev_t dev, ggml_backend_dev_props * props) {
+    ggml_backend_cuda_device_context * ctx = (ggml_backend_cuda_device_context *)dev->context;
+
     props->name        = ggml_backend_cuda_device_get_name(dev);
     props->description = ggml_backend_cuda_device_get_description(dev);
     props->type        = ggml_backend_cuda_device_get_type(dev);
+    props->device_id   = ctx->pci_bus_id.empty() ? nullptr : ctx->pci_bus_id.c_str();
     ggml_backend_cuda_device_get_memory(dev, &props->memory_free, &props->memory_total);
 
     bool host_buffer = getenv("GGML_CUDA_NO_PINNED") == nullptr;
@@ -3804,6 +3808,10 @@ ggml_backend_reg_t ggml_backend_cuda_reg() {
                 CUDA_CHECK(cudaGetDeviceProperties(&prop, i));
                 dev_ctx->description = prop.name;
 
+                char pci_bus_id[16] = {};
+                snprintf(pci_bus_id, sizeof(pci_bus_id), "%04x:%02x:%02x.0", prop.pciDomainID, prop.pciBusID, prop.pciDeviceID);
+                dev_ctx->pci_bus_id = pci_bus_id;
+
                 ggml_backend_dev_t dev = new ggml_backend_device {
                     /* .iface   = */ ggml_backend_cuda_device_interface,
                     /* .reg     = */ &reg,
diff --git a/ggml/src/ggml-vulkan/ggml-vulkan.cpp b/ggml/src/ggml-vulkan/ggml-vulkan.cpp
@@ -12113,13 +12113,15 @@ static ggml_backend_buffer_type_t ggml_backend_vk_device_get_host_buffer_type(gg
 
 static enum ggml_backend_dev_type ggml_backend_vk_device_get_type(ggml_backend_dev_t dev) {
     UNUSED(dev);
+    // TODO: return GGML_BACKEND_DEVICE_TYPE_IGPU for integrated GPUs
     return GGML_BACKEND_DEVICE_TYPE_GPU;
 }
 
 static void ggml_backend_vk_device_get_props(ggml_backend_dev_t dev, struct ggml_backend_dev_props * props) {
     props->name        = ggml_backend_vk_device_get_name(dev);
     props->description = ggml_backend_vk_device_get_description(dev);
     props->type        = ggml_backend_vk_device_get_type(dev);
+    // TODO: set props->device_id to PCI bus id
     ggml_backend_vk_device_get_memory(dev, &props->memory_free, &props->memory_total);
     props->caps = {
         /* .async                 = */ false,
diff --git a/src/llama.cpp b/src/llama.cpp
@@ -59,6 +59,7 @@ bool llama_supports_mlock(void) {
 
 bool llama_supports_gpu_offload(void) {
     return ggml_backend_dev_by_type(GGML_BACKEND_DEVICE_TYPE_GPU) != nullptr ||
+           ggml_backend_dev_by_type(GGML_BACKEND_DEVICE_TYPE_IGPU) != nullptr ||
            llama_supports_rpc();
 }
 
@@ -184,8 +185,13 @@ static struct llama_model * llama_model_load_from_file_impl(
             model->devices.push_back(*dev);
         }
     } else {
+        // default device selection
+
+        // build list of available devices
+        std::vector<ggml_backend_dev_t> gpus;
+        std::vector<ggml_backend_dev_t> igpus;
         std::vector<ggml_backend_dev_t> rpc_servers;
-        // use all available devices
+
         for (size_t i = 0; i < ggml_backend_dev_count(); ++i) {
             ggml_backend_dev_t dev = ggml_backend_dev_get(i);
             switch (ggml_backend_dev_type(dev)) {
@@ -194,19 +200,51 @@ static struct llama_model * llama_model_load_from_file_impl(
                     // skip CPU backends since they are handled separately
                     break;
 
-                case GGML_BACKEND_DEVICE_TYPE_GPU:
+                case GGML_BACKEND_DEVICE_TYPE_GPU: {
                     ggml_backend_reg_t reg = ggml_backend_dev_backend_reg(dev);
                     if (ggml_backend_reg_name(reg) == std::string("RPC")) {
                         rpc_servers.push_back(dev);
                     } else {
-                        model->devices.push_back(dev);
+                        // check if there is already a GPU with the same device id
+                        ggml_backend_dev_props props;
+                        ggml_backend_dev_get_props(dev, &props);
+                        auto it = std::find_if(gpus.begin(), gpus.end(), [&props](ggml_backend_dev_t d) {
+                            ggml_backend_dev_props d_props;
+                            ggml_backend_dev_get_props(d, &d_props);
+                            if (props.device_id && d_props.device_id) {
+                                return strcmp(props.device_id, d_props.device_id) == 0;
+                            }
+                            return false;
+                        });
+
+                        if (it != gpus.end()) {
+                            LLAMA_LOG_INFO("%s: skipping device %s (%s) with id %s - already using device %s (%s) with the same id\n",
+                                    __func__,
+                                    ggml_backend_dev_name(dev), ggml_backend_dev_description(dev),
+                                    props.device_id ? props.device_id : "unknown id",
+                                    ggml_backend_dev_name(*it), ggml_backend_dev_description(*it));
+                        } else {
+                            gpus.push_back(dev);
+                        }
                     }
                     break;
+                }
+
+                case GGML_BACKEND_DEVICE_TYPE_IGPU:
+                    igpus.push_back(dev);
+                    break;
             }
         }
-        // add RPC servers at the front of the list
-        if (!rpc_servers.empty()) {
-            model->devices.insert(model->devices.begin(), rpc_servers.begin(), rpc_servers.end());
+
+        // add RPC servers at the front of the list to minimize network transfers
+        model->devices.insert(model->devices.begin(), rpc_servers.begin(), rpc_servers.end());
+
+        // add GPUs
+        model->devices.insert(model->devices.end(), gpus.begin(), gpus.end());
+
+        // add integrated GPUs only if no other devices were found
+        if (model->devices.empty()) {
+            model->devices.insert(model->devices.end(), igpus.begin(), igpus.end());
         }
     }
 
@@ -227,9 +265,12 @@ static struct llama_model * llama_model_load_from_file_impl(
     }
 
     for (auto * dev : model->devices) {
-        size_t free, total; // NOLINT
-        ggml_backend_dev_memory(dev, &free, &total);
-        LLAMA_LOG_INFO("%s: using device %s (%s) - %zu MiB free\n", __func__, ggml_backend_dev_name(dev), ggml_backend_dev_description(dev), free/1024/1024);
+        ggml_backend_dev_props props;
+        ggml_backend_dev_get_props(dev, &props);
+        LLAMA_LOG_INFO("%s: using device %s (%s) (%s) - %zu MiB free\n", __func__,
+                ggml_backend_dev_name(dev), ggml_backend_dev_description(dev),
+                props.device_id ? props.device_id : "unknown id",
+                props.memory_free/1024/1024);
     }
 
     const int status = llama_model_load(path_model, splits, *model, params);
diff --git a/tools/llama-bench/llama-bench.cpp b/tools/llama-bench/llama-bench.cpp
@@ -128,7 +128,7 @@ static std::string get_gpu_info() {
     for (size_t i = 0; i < ggml_backend_dev_count(); i++) {
         auto * dev      = ggml_backend_dev_get(i);
         auto   dev_type = ggml_backend_dev_type(dev);
-        if (dev_type == GGML_BACKEND_DEVICE_TYPE_GPU) {
+        if (dev_type == GGML_BACKEND_DEVICE_TYPE_GPU || dev_type == GGML_BACKEND_DEVICE_TYPE_IGPU) {
             gpu_list.push_back(ggml_backend_dev_description(dev));
         }
     }
@@ -945,6 +945,7 @@ struct cmd_params_instance {
                         exit(1);
                     }
                 }
+                // FIXME: use llama.cpp device selection logic
                 // add local GPU devices if any
                 for (size_t i = 0; i < ggml_backend_dev_count(); ++i) {
                     ggml_backend_dev_t dev = ggml_backend_dev_get(i);
@@ -957,6 +958,10 @@ struct cmd_params_instance {
                         case GGML_BACKEND_DEVICE_TYPE_GPU:
                             devices.push_back(dev);
                             break;
+
+                        case GGML_BACKEND_DEVICE_TYPE_IGPU:
+                            // iGPUs are not used when there are RPC servers
+                            break;
                     }
                 }
                 devices.push_back(nullptr);

Original file line number	Diff line number	Diff line change
`@@ -128,7 +128,7 @@ static std::string get_gpu_info() {`
`128`	`128`	`for (size_t i = 0; i < ggml_backend_dev_count(); i++) {`
`129`	`129`	`auto * dev = ggml_backend_dev_get(i);`
`130`	`130`	`auto dev_type = ggml_backend_dev_type(dev);`
`131`		`- if (dev_type == GGML_BACKEND_DEVICE_TYPE_GPU) {`
	`131`	`+ if (dev_type == GGML_BACKEND_DEVICE_TYPE_GPU \|\| dev_type == GGML_BACKEND_DEVICE_TYPE_IGPU) {`
`132`	`132`	`gpu_list.push_back(ggml_backend_dev_description(dev));`
`133`	`133`	`}`
`134`	`134`	`}`
`@@ -945,6 +945,7 @@ struct cmd_params_instance {`
`945`	`945`	`exit(1);`
`946`	`946`	`}`
`947`	`947`	`}`
	`948`	`+ // FIXME: use llama.cpp device selection logic`
`948`	`949`	`// add local GPU devices if any`
`949`	`950`	`for (size_t i = 0; i < ggml_backend_dev_count(); ++i) {`
`950`	`951`	`ggml_backend_dev_t dev = ggml_backend_dev_get(i);`
`@@ -957,6 +958,10 @@ struct cmd_params_instance {`
`957`	`958`	`case GGML_BACKEND_DEVICE_TYPE_GPU:`
`958`	`959`	`devices.push_back(dev);`
`959`	`960`	`break;`
	`961`	`+`
	`962`	`+ case GGML_BACKEND_DEVICE_TYPE_IGPU:`
	`963`	`+ // iGPUs are not used when there are RPC servers`
	`964`	`+ break;`
`960`	`965`	`}`
`961`	`966`	`}`
`962`	`967`	`devices.push_back(nullptr);`