Split View: [가상화] 04. GPU 가상화 기술 총정리: Passthrough, vGPU, MIG, SR-IOV

[GPU Virtualization Technology Spectrum]

Exclusive <----------------------------------------> Maximum Sharing

GPU Passthrough    vGPU (SR-IOV)    MIG    vGPU (mdev)    Time-Slicing
 (1 GPU : 1 VM)   (HW partition)  (spatial) (SW timeslice)  (K8s share)

+------------------+     +------------------+
|    VM 1          |     |    VM 2          |
|  GPU Driver      |     |  GPU Driver      |
|  (Full Access)   |     |  (Full Access)   |
+--------+---------+     +--------+---------+
         |                         |
    IOMMU/VT-d                IOMMU/VT-d
         |                         |
+--------+---------+     +--------+---------+
|  Physical GPU 1  |     |  Physical GPU 2  |
|  (Exclusive)     |     |  (Exclusive)     |
+------------------+     +------------------+

# 1. Enable VT-d/AMD-Vi (IOMMU) in BIOS

# 2. Add IOMMU to boot parameters
# /etc/default/grub:
# GRUB_CMDLINE_LINUX="intel_iommu=on iommu=pt"

# 3. Check IOMMU groups
find /sys/kernel/iommu_groups/ -type l | sort -V

# 4. Bind GPU to vfio-pci driver
# /etc/modprobe.d/vfio.conf:
# options vfio-pci ids=10de:2484,10de:228b

# 5. Rebuild initramfs
update-initramfs -u

# 6. Verify after reboot
lspci -nnk -s 01:00.0
# Kernel driver in use: vfio-pci

+--------+ +--------+ +--------+ +--------+
| VM 1   | | VM 2   | | VM 3   | | VM 4   |
| vGPU   | | vGPU   | | vGPU   | | vGPU   |
| 4GB    | | 4GB    | | 4GB    | | 4GB    |
+--------+ +--------+ +--------+ +--------+
|            vGPU Manager                  |
|        (Hypervisor Module)               |
+------------------------------------------+
|          Physical GPU (16GB)             |
|        (NVIDIA A100/L40S/etc.)          |
+------------------------------------------+

[Software Time-Slicing]

Time -->  |  VM1  |  VM2  |  VM3  |  VM1  |  VM2  |  VM3  |
          +-------+-------+-------+-------+-------+-------+
Full GPU   used    used    used    used    used    used

- Entire GPU shared via time-division
- vGPU Manager handles context switching
- VRAM statically partitioned
- Compute resources time-shared

[Hardware Partitioning - SR-IOV]

+-------------------------------------------+
| Physical Function (PF)                     |
| - GPU management and configuration        |
+-------------------------------------------+
| VF 0        | VF 1        | VF 2          |
| (VM 1)      | (VM 2)      | (VM 3)        |
| Own queues  | Own queues  | Own queues     |
| Own IRQs    | Own IRQs    | Own IRQs       |
+-------------------------------------------+
|          Physical GPU (PCIe)              |
+-------------------------------------------+

- PF (Physical Function): Managed by host
- VF (Virtual Function): Directly assigned to each VM
- IOMMU ensures memory isolation between VFs
- Hardware-level isolation for better stability

[NVIDIA A100 vGPU Profile Examples]

GPU: NVIDIA A100 40GB

Profile           VRAM    Max Instances
A100-1-5C         5GB      7
A100-2-10C       10GB      4
A100-4-20C       20GB      2
A100-8-40C       40GB      1
A100-1-5CME       5GB      7  (MIG-backed)
A100-2-10CME     10GB      4  (MIG-backed)

[MIG Architecture - A100 Example]

+-----------------------------------------------------------+
|                    NVIDIA A100 (80GB)                       |
+-----------------------------------------------------------+
| GPC 0-1  | GPC 2-3  | GPC 4   | GPC 5   | GPC 6          |
| MIG 1    | MIG 2    | MIG 3   | MIG 4   | MIG 5          |
| 2g.20gb  | 2g.20gb  | 1g.10gb | 1g.10gb | 1g.10gb        |
+----------+----------+---------+---------+-----------------+
| Memory   | Memory   | Memory  | Memory  | Memory          |
| Ctrl 0-1 | Ctrl 2-3 | Ctrl 4  | Ctrl 5  | Ctrl 6          |
| 20GB HBM | 20GB HBM | 10GB HBM| 10GB HBM| 10GB HBM       |
+----------+----------+---------+---------+-----------------+
| L2 Cache | L2 Cache | L2 $    | L2 $    | L2 $            |
| Slice 0-1| Slice 2-3| Slice 4 | Slice 5 | Slice 6         |
+-----------------------------------------------------------+

# Enable MIG mode (reboot required)
sudo nvidia-smi -i 0 --mig 1

# After reboot, create MIG instances
# List available profiles
nvidia-smi mig -lgip

# Create two 3g.40gb instances (A100 80GB)
sudo nvidia-smi mig -cgi 9,9 -C

# Verify created instances
nvidia-smi mig -lgi
nvidia-smi mig -lci

# Delete MIG instances
sudo nvidia-smi mig -dci
sudo nvidia-smi mig -dgi

# Disable MIG mode (reboot required)
sudo nvidia-smi -i 0 --mig 0

+--------+ +--------+ +--------+
| VM 1   | | VM 2   | | VM 3   |
| vGPU   | | vGPU   | | vGPU   |
+--------+ +--------+ +--------+
| vGPU Manager                  |
+------+-------+-------+-------+
| MIG 1| MIG 2 | MIG 3 | MIG 4 |  <-- Hardware isolation
+------+-------+-------+-------+
|        Physical GPU           |
+-------------------------------+

- Between MIG slices: Hardware isolation
- Multiple vGPUs within same MIG: Time-slicing

[SR-IOV Structure]

PCIe Bus
    |
+---+---+---+---+---+---+
| PF    | VF 0 | VF 1 | VF 2 |
| (Host)| (VM1)| (VM2)| (VM3)|
+-------+------+------+------+
|          Physical GPU       |
+-----------------------------+

PF = Physical Function (host management)
VF = Virtual Function (direct VM assignment)

[K8s GPU Time-Slicing]

+---Pod A---+ +---Pod B---+ +---Pod C---+
|  Process  | |  Process  | |  Process  |
|  CUDA     | |  CUDA     | |  CUDA     |
+-----------+ +-----------+ +-----------+
|    NVIDIA Device Plugin (time-slicing)  |
+-----------------------------------------+
|          Physical GPU                   |
|     (shared by all processes)           |
+-----------------------------------------+

- NVIDIA GPU Operator TimeSlicing configuration
- No hardware isolation
- Shared memory space (OOM possible)
- MPS (Multi-Process Service) option for better performance

# NVIDIA GPU Operator ConfigMap example
# time-slicing-config
apiVersion: v1
kind: ConfigMap
metadata:
  name: time-slicing-config
data:
  any: |-
    version: v1
    flags:
      migStrategy: none
    sharing:
      timeSlicing:
        renameByDefault: false
        failRequestsGreaterThanOne: false
        resources:
          - name: nvidia.com/gpu
            replicas: 4

[GPU Virtualization Selection Flowchart]

Start: Do you need to share the GPU?
  |
  +-- No --> GPU Passthrough
  |          (Best performance, 1:1 assignment)
  |
  +-- Yes --> Do you need hardware isolation?
               |
               +-- No --> Is this Kubernetes?
               |           |
               |           +-- Yes --> Time-Slicing
               |           |          (Simplest approach)
               |           |
               |           +-- No --> vGPU (mdev)
               |                      (VM-based sharing)
               |
               +-- Yes --> MIG-capable GPU (A100/H100)?
                           |
                           +-- Yes --> MIG or MIG-backed vGPU
                           |          (Best isolation)
                           |
                           +-- No --> vGPU (SR-IOV)
                                      (Ampere+ HW partitioning)