[PATCH v2 0/7] migration/multifd: Some VFIO / postcopy preparations on flush

[Peter Xu]

CI: https://gitlab.com/peterx/qemu/-/pipelines/1575970314

Comparing to v1, this series v2 now contains some patches that may be
helpful for either VFIO or postcopy integration on top of multifd.

For VFIO, only patch 1 & 2 are relevant.  This is the only part that can be
compared to v1, where I renamed the sync flag to LOCAL and ALL according to
Fabiano's comment.

For postcopy, it's about patches 3-7, but it needs to be based on 1+2.

I put them together because the two changes are relevant on the multifd
sync operation, one must depend on another in some form. So I decided to
send them together here.  All these patches can be seen as cleanups /
slight optimizations on top of master branch.

This time I did more test.  Besides CI, qtests, and some real-world multifd
tests just to monitor the sync events happen all correct, I made sure to
cover 7.2 machine type (which uses the legacy sync) so it still works as
before - basically sync will be more frequent, but all thing keeps working
smoothly so far.

Fabiano, let me know what do you think comparing to the other patch [1] on
simplifying the flush checks.  I'm open to any comments.

Thanks,

[1] https://lore.kernel.org/r/875xo8n4ue.fsf@suse.de

Thanks,

Peter Xu (7):
  migration/multifd: Further remove the SYNC on complete
  migration/multifd: Allow to sync with sender threads only
  migration/ram: Move RAM_SAVE_FLAG* into ram.h
  migration/multifd: Unify RAM_SAVE_FLAG_MULTIFD_FLUSH messages
  migration/multifd: Remove sync processing on postcopy
  migration/multifd: Cleanup src flushes on condition check
  migration/multifd: Document the reason to sync for save_setup()

 migration/multifd.h        | 23 ++++++++--
 migration/ram.h            | 25 +++++++++++
 migration/rdma.h           |  7 ---
 migration/multifd-nocomp.c | 74 ++++++++++++++++++++++++++++++-
 migration/multifd.c        | 15 ++++---
 migration/ram.c            | 91 +++++++++++++++++---------------------
 6 files changed, 166 insertions(+), 69 deletions(-)

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2.47.0