[Qemu-devel] KVM call minutes for Sept 14

[Chris Wright]

0.13
- if all goes well...tomorrow

stable tree
- please look at -stable to see what is missing (bugfixes)
  - esp. regressions from 0.12
- looking for dedicated stable maintainer/release manager
  - pick this discussion up next week

qed/qcow2
- increase concurrency, performance
- threading vs state machine
- avi doesn't like qed reliance on fsck
  - undermines value of error checking (errors become normal)
  - prefer preallocation and fsck just checks for leaked blocks
- just load and validate metadata
- options for correctness are
  - fsync at every data allocation
  - leak data blocks
  - scan
- qed is pure statemachine
  - state on stack, control flow vs function call
- common need to separate handle requests concurrently, issue async i/o
- most disk formats have similar metadata and methods
  - lookup cluster, read/write data
  - qed could be a path to cleaning up other formats (reusing)
- need an incremental way to improve qcow2 performance
  - threading doesn't seem to be the way to achieve this (incrementally)
- coroutines vs. traditional threads discussion
  - parallel (and locking) vs few well-defined preemption points
- plan for qed...attempt to merge in 0.14
  - online fsck support is all that's missing
  - add bdrv check callback, look for new patch series over the next week
- back to list with discussion...