Function ggml_cl_pool_malloc

ggml-opencl.cpp:1277–1317

static std::atomic_flag g_cl_pool_lock = ATOMIC_FLAG_INIT;

static cl_mem ggml_cl_pool_malloc(size_t size, size_t * actual_size) {
    scoped_spin_lock lock(g_cl_pool_lock);
    cl_int err;

    int best_i = -1;
    size_t best_size = std::numeric_limits<size_t>::max(); //smallest unused buffer that fits our needs
    int worst_i = -1;
    size_t worst_size = 0; //largest unused buffer seen so far
    for (int i = 0; i < MAX_CL_BUFFERS; ++i) {
        cl_buffer &b = g_cl_buffer_pool[i];
        if (b.size > 0 && b.size >= size && b.size < best_size)
        {
            best_i = i;
            best_size = b.size;
        }
        if (b.size > 0 && b.size > worst_size)
        {
            worst_i = i;
            worst_size = b.size;
        }
    }
    if(best_i!=-1) //found the smallest buffer that fits our needs
    {
        cl_buffer& b = g_cl_buffer_pool[best_i];
        cl_mem mem = b.mem;
        *actual_size = b.size;
        b.size = 0;
        return mem;
    }
    if(worst_i!=-1) //no buffer that fits our needs, resize largest one to save memory
    {
         cl_buffer& b = g_cl_buffer_pool[worst_i];
         cl_mem mem = b.mem;
         b.size = 0;
         clReleaseMemObject(mem);
    }
    cl_mem mem;
    CL_CHECK((mem = clCreateBuffer(context, CL_MEM_READ_WRITE, size, NULL, &err), err));
    *actual_size = size;
    return mem;
}

static void ggml_cl_pool_free(cl_mem mem, size_t size) {
    scoped_spin_lock lock(g_cl_pool_lock);