VK_NV_external_memory_rdma

Other Extension Metadata

Last Modified Date

2021-04-19

IP Status

No known IP claims.

Contributors
  • Carsten Rohde, NVIDIA

Description

This extension adds support for allocating memory which can be used for remote direct memory access (RDMA) from other devices.

New Base Types

New Commands

New Structures

New Enum Constants

  • VK_NV_EXTERNAL_MEMORY_RDMA_EXTENSION_NAME
  • VK_NV_EXTERNAL_MEMORY_RDMA_SPEC_VERSION
  • Extending VkExternalMemoryHandleTypeFlagBits:
    • VK_EXTERNAL_MEMORY_HANDLE_TYPE_RDMA_ADDRESS_BIT_NV
  • Extending VkMemoryPropertyFlagBits:
    • VK_MEMORY_PROPERTY_RDMA_CAPABLE_BIT_NV
  • Extending VkStructureType:
    • VK_STRUCTURE_TYPE_MEMORY_GET_REMOTE_ADDRESS_INFO_NV
    • VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_EXTERNAL_MEMORY_RDMA_FEATURES_NV

Issues

Examples

VkPhysicalDeviceMemoryBudgetPropertiesEXT memoryBudgetProperties = { VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_MEMORY_BUDGET_PROPERTIES_EXT };
VkPhysicalDeviceMemoryProperties2 memoryProperties2 = { VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_MEMORY_PROPERTIES_2, &memoryBudgetProperties };
vkGetPhysicalDeviceMemoryProperties2(physicalDevice, &memoryProperties2);
uint32_t heapIndex = (uint32_t)-1;
for (uint32_t memoryType = 0; memoryType < memoryProperties2.memoryProperties.memoryTypeCount; memoryType++) {
    if (memoryProperties2.memoryProperties.memoryTypes[memoryType].propertyFlags & VK_MEMORY_PROPERTY_RDMA_CAPABLE_BIT_NV) {
        heapIndex = memoryProperties2.memoryProperties.memoryTypes[memoryType].heapIndex;
        break;
    }
}
if ((heapIndex == (uint32_t)-1) ||
    (memoryBudgetProperties.heapBudget[heapIndex] < size)) {
    return;
}

VkPhysicalDeviceExternalBufferInfo externalBufferInfo = { VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_EXTERNAL_BUFFER_INFO };
externalBufferInfo.usage = VK_BUFFER_USAGE_TRANSFER_SRC_BIT | VK_BUFFER_USAGE_TRANSFER_DST_BIT;
externalBufferInfo.handleType = VK_EXTERNAL_MEMORY_HANDLE_TYPE_RDMA_ADDRESS_BIT_NV;

VkExternalBufferProperties externalBufferProperties = { VK_STRUCTURE_TYPE_EXTERNAL_BUFFER_PROPERTIES };
vkGetPhysicalDeviceExternalBufferProperties(physicalDevice, &externalBufferInfo, &externalBufferProperties);

if (!(externalBufferProperties.externalMemoryProperties.externalMemoryFeatures & VK_EXTERNAL_MEMORY_FEATURE_EXPORTABLE_BIT)) {
    return;
}

VkExternalMemoryBufferCreateInfo externalMemoryBufferCreateInfo = { VK_STRUCTURE_TYPE_EXTERNAL_MEMORY_BUFFER_CREATE_INFO };
externalMemoryBufferCreateInfo.handleTypes = VK_EXTERNAL_MEMORY_HANDLE_TYPE_RDMA_ADDRESS_BIT_NV;

VkBufferCreateInfo bufferCreateInfo = { VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO, &externalMemoryBufferCreateInfo };
bufferCreateInfo.size = size;
bufferCreateInfo.usage = VK_BUFFER_USAGE_TRANSFER_SRC_BIT | VK_BUFFER_USAGE_TRANSFER_DST_BIT;

VkMemoryRequirements mem_reqs;
vkCreateBuffer(device, &bufferCreateInfo, NULL, &buffer);
vkGetBufferMemoryRequirements(device, buffer, &mem_reqs);

VkExportMemoryAllocateInfo exportMemoryAllocateInfo = { VK_STRUCTURE_TYPE_EXPORT_MEMORY_ALLOCATE_INFO };
exportMemoryAllocateInfo.handleTypes = VK_EXTERNAL_MEMORY_HANDLE_TYPE_RDMA_ADDRESS_BIT_NV;

// Find memory type index
uint32_t i = 0;
for (; i < VK_MAX_MEMORY_TYPES; i++) {
    if ((mem_reqs.memoryTypeBits & (1 << i)) &&
        (memoryProperties.memoryTypes[i].propertyFlags & VK_MEMORY_PROPERTY_RDMA_CAPABLE_BIT_NV)) {
        break;
    }
}

VkMemoryAllocateInfo memAllocInfo = { VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO, &exportMemoryAllocateInfo };
memAllocInfo.allocationSize = mem_reqs.size;
memAllocInfo.memoryTypeIndex = i;

vkAllocateMemory(device, &memAllocInfo, NULL, &mem);
vkBindBufferMemory(device, buffer, mem, 0);

VkMemoryGetRemoteAddressInfoNV getMemoryRemoteAddressInfo = { VK_STRUCTURE_TYPE_MEMORY_GET_REMOTE_ADDRESS_INFO_NV };
getMemoryRemoteAddressInfo.memory = mem;
getMemoryRemoteAddressInfo.handleType = VK_EXTERNAL_MEMORY_HANDLE_TYPE_RDMA_ADDRESS_BIT_NV;

VkRemoteAddressNV rdmaAddress;
vkGetMemoryRemoteAddressNV(device, &getMemoryRemoteAddressInfo, &rdmaAddress);
// address returned in 'rdmaAddress' can be used by external devices to initiate RDMA transfers

Version History

  • Revision 1, 2020-12-15 (Carsten Rohde)
    • Internal revisions