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[0/5] Allow to enable multifd and postcopy migration together

Message ID 20241029150908.1136894-1-ppandit@redhat.com (mailing list archive)
Headers show
Series Allow to enable multifd and postcopy migration together | expand

Message

Prasad Pandit Oct. 29, 2024, 3:09 p.m. UTC 
From: Prasad Pandit <pjp@fedoraproject.org>

Hello,

* Currently Multifd and Postcopy migration can not be used together.
  QEMU shows "Postcopy is not yet compatible with multifd" message.

  When migrating guests with large (100's GB) RAM, Multifd threads
  help to accelerate migration, but inability to use it with the
  Postcopy mode delays guest start up on the destination side.

* This patch series allows to enable both Multifd and Postcopy
  migration together. In this, Precopy and Multifd threads work
  during the initial guest (RAM) transfer. When migration moves
  to the Postcopy phase, Precopy and Multifd threads on the source
  side stop sending data on their channels. Instead Postcopy threads
  on the destination start to request pages from the source side.

* This series introduces magic value (4-bytes) to be sent on the
  Postcopy channel. It helps to differentiate channels and properly
  setup incoming connections on the destination side.

Thank you.
---
Prasad Pandit (5):
  migration/multifd: move macros to multifd header
  migration/postcopy: magic value for postcopy channel
  migration: remove multifd check with postcopy
  migration: refactor ram_save_target_page functions
  migration: enable multifd and postcopy together

 migration/migration.c    | 73 ++++++++++++++++++++++++----------------
 migration/multifd.c      |  4 ---
 migration/multifd.h      |  5 +++
 migration/options.c      |  8 ++---
 migration/postcopy-ram.c |  7 ++++
 migration/postcopy-ram.h |  3 ++
 migration/ram.c          | 54 ++++++++++++-----------------
 7 files changed, 83 insertions(+), 71 deletions(-)

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2.47.0