Virtual Versus Physical: Virtio Changes for New Hardware
summary
Virtio adds concrete changes for hardware: a packed ring descriptor layout plus driver-sent last-available offset reduces PCIe transactions to one read and two writes per descriptor; a batch-commit feature lets the device announce many buffers by writing only the last descriptor; hardware-visible page-fault support enables thousands of virtual functions and enables post-copy live migration by fetching missing pages on fault; a new descriptor flag lets in-order optimization coexist with page-fault handling; wrap-detection lets a single PCIe write mark multiple used descriptors.
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chapters (19)
- 0:00Virtual versus physical
- 0:48Virtio Interface Zoo
- 1:53Why hardware virtio?
- 4:53Split Virtqueue
- 6:39Packed Virtqueue: portability
- 7:36Remove flags read
- 8:30Reduce number of writes
- 13:14Virtio net RX stalls
- 13:57Out of order use of buffers
- 15:16VIRTIO_F_PARTIAL_ORDER
- 16:31Page faults: more goodies
- 17:41Post copy migration
- 19:48Live migration solutions
- 20:54Live migration issues
- 21:54Cross-vendor compatibility
- 24:54Descriptor fragmentation (cont.)
- 25:50Descriptor fragmentation avoidance
- 27:01Summary
- 27:31Questions?
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