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ExtraVirt: Detecting and recovering from transient processor faults

Dominic Lucchetti, Steve Reinhardt, Peter Chen

University of Michigan

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Flips Happen

Similar die area+

Decreasing transition energy=

Increasing risk of transient failure

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Multi-Processors &Virtual Machine

Multi-Processor Ensure error

independence Enable fault detection Efficient resource sharing

Virtual Machine No changes to OS or

applications VM replay

Synchronize replicas Recover correct state

Replica 1 Replica 2

Hypervisor

DeviceDrivers

Replication Management Layer (RML)

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Example: Memory

Copy on write Reduces overhead Protects checkpoints

Merge on checkpoint Verify correctness Re-execute on

deviation Memory Fault

Protection ECC against RAM

faults MMU against CPU

faults

Memory CheckpointReplica 1Checkpoint Replica 2

A

B

CD

E

A

B

CX

E

A

B

C

E

Verify

Replica 3

A

B

CD

E

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Status

Present VM Replay Beginnings of Replication

Management Layer (RML) Still much to do…

Future Replicate the un-replicated Handle faults in device

drivers Expanded fault model

Replica 1 Replica 2

Hypervisor/RML

DeviceDrivers

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Questions?