10 MB Allocation on GPU During VkInstance creation, not VkDevice creation

[Prox501]

So I have noticed an over-eager behavior in allocating 10 MB of memory on GPU. I was able to reproduce the behavior with the following code in C language:

#include <vulkan/vulkan.h>
#include <stdio.h>
#include <stdlib.h>

int main() {
    VkInstance instance;

    VkApplicationInfo appInfo = {
        .sType = VK_STRUCTURE_TYPE_APPLICATION_INFO,
        .pApplicationName = "VkInstanceTest",
        .applicationVersion = VK_MAKE_VERSION(1, 0, 0),
        .pEngineName = "NoEngine",
        .engineVersion = VK_MAKE_VERSION(1, 0, 0),
        .apiVersion = VK_API_VERSION_1_0
    };

    VkInstanceCreateInfo createInfo = {
        .sType = VK_STRUCTURE_TYPE_INSTANCE_CREATE_INFO,
        .pApplicationInfo = &appInfo
    };

    VkResult result = vkCreateInstance(&createInfo, NULL, &instance);
    if (result != VK_SUCCESS) {
        fprintf(stderr, "Failed to create Vulkan instance! Error code: %d\n", result);
        return EXIT_FAILURE;
    }

    printf("VkInstance created successfully.\n");
    printf("Press Enter to exit...\n");
    getchar();  // Wait for user to press Enter

    vkDestroyInstance(instance, NULL);
    printf("VkInstance destroyed.\n");

    return EXIT_SUCCESS;
}

And you can build it by running clang -lvulkan demo.c -o demovulkan assuming that the c file is demo.c. When running with nvtop program which tracks real-time usage of GPU memory, on your AMDVLK, it over-eagerly allocate 10 MB on the GPU without a reason to when VkDevice have yet to be allocated or built when running above code. So if you instead point to using RADV driver, it reports either 0 mb allocation on GPU or not showing up at nvtop at all.

VK_ICD_FILENAMES=/usr/share/vulkan/icd.d/radeon_icd.x86_64.json ./demovulkan

Thanks.