ggml-backend.h

#pragma once

#include "ggml.h"
#include "ggml-alloc.h"

#ifdef  __cplusplus
extern "C" {
#endif

    typedef struct ggml_backend_buffer_type * ggml_backend_buffer_type_t;
    typedef struct ggml_backend_buffer * ggml_backend_buffer_t;
    typedef struct ggml_backend * ggml_backend_t;
    typedef void * ggml_backend_graph_plan_t;

    //
    // Backend buffer
    //

    // buffer type
    GGML_API           const char *          ggml_backend_buft_name            (ggml_backend_buffer_type_t buft);
    GGML_API GGML_CALL ggml_backend_buffer_t ggml_backend_buft_alloc_buffer    (ggml_backend_buffer_type_t buft, size_t size);
    GGML_API           size_t                ggml_backend_buft_get_alignment   (ggml_backend_buffer_type_t buft);
    GGML_API           size_t                ggml_backend_buft_get_max_size    (ggml_backend_buffer_type_t buft);
    GGML_API GGML_CALL size_t                ggml_backend_buft_get_alloc_size  (ggml_backend_buffer_type_t buft, struct ggml_tensor * tensor);
    GGML_API           bool                  ggml_backend_buft_supports_backend(ggml_backend_buffer_type_t buft, ggml_backend_t backend);
    GGML_API           bool                  ggml_backend_buft_is_host         (ggml_backend_buffer_type_t buft);

    // buffer
    enum ggml_backend_buffer_usage {
        GGML_BACKEND_BUFFER_USAGE_ANY = 0,
        GGML_BACKEND_BUFFER_USAGE_WEIGHTS = 1,
    };

    GGML_API           const char *               ggml_backend_buffer_name          (ggml_backend_buffer_t buffer);
    GGML_API           void                       ggml_backend_buffer_free          (ggml_backend_buffer_t buffer);
    GGML_API           void *                     ggml_backend_buffer_get_base      (ggml_backend_buffer_t buffer);
    GGML_API           size_t                     ggml_backend_buffer_get_size      (ggml_backend_buffer_t buffer);
    GGML_API GGML_CALL void                       ggml_backend_buffer_init_tensor   (ggml_backend_buffer_t buffer, struct ggml_tensor * tensor);
    GGML_API           size_t                     ggml_backend_buffer_get_alignment (ggml_backend_buffer_t buffer);
    GGML_API           size_t                     ggml_backend_buffer_get_max_size  (ggml_backend_buffer_t buffer);
    GGML_API           size_t                     ggml_backend_buffer_get_alloc_size(ggml_backend_buffer_t buffer, struct ggml_tensor * tensor);
    GGML_API           void                       ggml_backend_buffer_clear         (ggml_backend_buffer_t buffer, uint8_t value);
    GGML_API           bool                       ggml_backend_buffer_is_host       (ggml_backend_buffer_t buffer);
    GGML_API           void                       ggml_backend_buffer_set_usage     (ggml_backend_buffer_t buffer, enum ggml_backend_buffer_usage usage);
    GGML_API           ggml_backend_buffer_type_t ggml_backend_buffer_get_type      (ggml_backend_buffer_t buffer);
    GGML_API           void                       ggml_backend_buffer_reset         (ggml_backend_buffer_t buffer);

    //
    // Backend
    //


    GGML_API const char * ggml_backend_name(ggml_backend_t backend);
    GGML_API void         ggml_backend_free(ggml_backend_t backend);

    GGML_API ggml_backend_buffer_type_t ggml_backend_get_default_buffer_type(ggml_backend_t backend);
    GGML_API ggml_backend_buffer_t      ggml_backend_alloc_buffer(ggml_backend_t backend, size_t size);
    GGML_API size_t                     ggml_backend_get_alignment(ggml_backend_t backend);
    GGML_API size_t                     ggml_backend_get_max_size(ggml_backend_t backend);

    GGML_API void ggml_backend_tensor_set_async(ggml_backend_t backend,       struct ggml_tensor * tensor, const void * data, size_t offset, size_t size);
    GGML_API void ggml_backend_tensor_get_async(ggml_backend_t backend, const struct ggml_tensor * tensor,       void * data, size_t offset, size_t size);

    GGML_API GGML_CALL void ggml_backend_tensor_set(      struct ggml_tensor * tensor, const void * data, size_t offset, size_t size);
    GGML_API GGML_CALL void ggml_backend_tensor_get(const struct ggml_tensor * tensor,       void * data, size_t offset, size_t size);

    GGML_API void ggml_backend_synchronize(ggml_backend_t backend);

    GGML_API ggml_backend_graph_plan_t ggml_backend_graph_plan_create (ggml_backend_t backend, struct ggml_cgraph * cgraph);

    GGML_API void ggml_backend_graph_plan_free   (ggml_backend_t backend, ggml_backend_graph_plan_t plan);
    GGML_API void ggml_backend_graph_plan_compute(ggml_backend_t backend, ggml_backend_graph_plan_t plan);
    GGML_API bool ggml_backend_graph_compute     (ggml_backend_t backend, struct ggml_cgraph * cgraph);
    GGML_API bool ggml_backend_supports_op       (ggml_backend_t backend, const struct ggml_tensor * op);

    // tensor copy between different backends
    GGML_API void ggml_backend_tensor_copy(struct ggml_tensor * src, struct ggml_tensor * dst);
    GGML_API void ggml_backend_tensor_copy_async(ggml_backend_t backend, struct ggml_tensor * src, struct ggml_tensor * dst); // automatic fallback to sync copy

    //
    // CPU backend
    //

    GGML_API ggml_backend_t ggml_backend_cpu_init(void);

    GGML_API GGML_CALL bool ggml_backend_is_cpu           (ggml_backend_t backend);
    GGML_API           void ggml_backend_cpu_set_n_threads(ggml_backend_t backend_cpu, int n_threads);

    // Create a backend buffer from an existing pointer
    GGML_API GGML_CALL ggml_backend_buffer_t ggml_backend_cpu_buffer_from_ptr(void * ptr, size_t size);

    GGML_API GGML_CALL ggml_backend_buffer_type_t ggml_backend_cpu_buffer_type(void);

#ifdef GGML_USE_CPU_HBM
    GGML_API ggml_backend_buffer_type_t ggml_backend_cpu_hbm_buffer_type(void);
#endif

    //
    // Backend registry
    //

    // The backend registry is a registry of all the available backends, and allows initializing backends in a generic way

    GGML_API size_t                     ggml_backend_reg_get_count(void);
    GGML_API size_t                     ggml_backend_reg_find_by_name(const char * name);
    GGML_API ggml_backend_t             ggml_backend_reg_init_backend_from_str(const char * backend_str); // str is name[:params]
    GGML_API const char *               ggml_backend_reg_get_name(size_t i);
    GGML_API ggml_backend_t             ggml_backend_reg_init_backend(size_t i, const char * params); // params is backend-specific
    GGML_API ggml_backend_buffer_type_t ggml_backend_reg_get_default_buffer_type(size_t i);
    GGML_API ggml_backend_buffer_t      ggml_backend_reg_alloc_buffer(size_t i, size_t size);

    //
    // Backend scheduler
    //

    // The backend scheduler allows for multiple backends to be used together
    // Handles compute buffer allocation, assignment of tensors to backends, and copying of tensors between backends
    // The backends are selected based on:
    // - the backend that supports the operation
    // - the location of the pre-allocated tensors (e.g. the weights)
    /*
      Example usage:

        sched = ggml_backend_sched_new({backend_gpu, backend_gpu2, backend_cpu}, num_backends);
        // sched is initialized with measure allocators and cannot be used until allocated with a measure graph

        // initialize buffers from a measure graph
        measure_graph = build_graph(sched); // use the allocr to allocate inputs as needed

        // in build_graph:
        build_graph(...) {
            // allocating tensors in a specific backend (optional, recommended: pre-allocate inputs in a different buffer)
            alloc_cpu = ggml_backend_sched_get_allocr(sched, backend_cpu);
            ggml_allocr_alloc(alloc_cpu, tensor);

            // manually assigning nodes to a backend (optional, shouldn't be needed in most cases)
            struct ggml_tensor * node = ggml_mul_mat(ctx, ...);
            ggml_backend_sched_set_node_backend(sched, node, backend_gpu);
        }

        // allocate backend buffers from measure graph
        ggml_backend_sched_init_measure(sched, measure_graph);

        // the scheduler is now ready to compute graphs

        // compute
        graph = build_graph(sched);
        ggml_backend_sched_graph_compute(sched, graph);
    */

    struct ggml_backend_sched;
    typedef struct ggml_backend_sched * ggml_backend_sched_t;

    // when ask == true, the scheduler wants to know if the user wants to observe this node
    // this allows the scheduler to batch nodes together in order to evaluate them in a single call
    //
    // when ask == false, the scheduler is passing the node tensor to the user for observation
    // if the user returns false, the scheduler will cancel the graph compute
    //
    typedef bool (*ggml_backend_sched_eval_callback)(struct ggml_tensor * t, bool ask, void * user_data);

    // Initialize a backend scheduler
    GGML_API ggml_backend_sched_t  ggml_backend_sched_new(ggml_backend_t * backends, ggml_backend_buffer_type_t * bufts, int n_backends, size_t graph_size);
    GGML_API void                  ggml_backend_sched_free(ggml_backend_sched_t sched);
    // Initialize backend buffers from a measure graph
    GGML_API void                  ggml_backend_sched_init_measure(ggml_backend_sched_t sched, struct ggml_cgraph * measure_graph);
    // Get the number of splits of the last graph
    GGML_API int                   ggml_backend_sched_get_n_splits(ggml_backend_sched_t sched);

    GGML_API ggml_tallocr_t        ggml_backend_sched_get_tallocr(ggml_backend_sched_t sched, ggml_backend_t backend);
    GGML_API ggml_backend_buffer_t ggml_backend_sched_get_buffer (ggml_backend_sched_t sched, ggml_backend_t backend);

    GGML_API void                  ggml_backend_sched_set_node_backend(ggml_backend_sched_t sched, struct ggml_tensor * node, ggml_backend_t backend);
    GGML_API ggml_backend_t        ggml_backend_sched_get_node_backend(ggml_backend_sched_t sched, struct ggml_tensor * node);

    // Allocate and compute graph on the backend scheduler
    GGML_API void                  ggml_backend_sched_graph_compute(ggml_backend_sched_t sched, struct ggml_cgraph * graph);

    // Reset all assignments and allocators - must be called before using the sched allocators to allocate inputs
    GGML_API void                  ggml_backend_sched_reset(ggml_backend_sched_t sched);

    // Set a callback to be called for each resulting node during graph compute
    GGML_API void                  ggml_backend_sched_set_eval_callback(ggml_backend_sched_t sched, ggml_backend_sched_eval_callback callback, void * user_data);

    //
    // Utils
    //

    struct ggml_backend_graph_copy {
        ggml_backend_buffer_t buffer;
        struct ggml_context * ctx_allocated;
        struct ggml_context * ctx_unallocated;
        struct ggml_cgraph * graph;
    };

    // Copy a graph to a different backend
    GGML_API struct ggml_backend_graph_copy ggml_backend_graph_copy(ggml_backend_t backend, struct ggml_cgraph * graph);
    GGML_API void                           ggml_backend_graph_copy_free(struct ggml_backend_graph_copy copy);

    typedef bool (*GGML_CALL ggml_backend_eval_callback)(int node_index, struct ggml_tensor * t1, struct ggml_tensor * t2, void * user_data);

    // Compare the output of two backends
    GGML_API bool ggml_backend_compare_graph_backend(ggml_backend_t backend1, ggml_backend_t backend2, struct ggml_cgraph * graph, ggml_backend_eval_callback callback, void * user_data);

    // Tensor initialization
    GGML_API void ggml_backend_tensor_alloc(ggml_backend_buffer_t buffer, struct ggml_tensor * tensor, void * addr);
    GGML_API void ggml_backend_view_init(ggml_backend_buffer_t buffer, struct ggml_tensor * tensor);


#ifdef  __cplusplus
}
#endif