[Patch v2 0/6] migration/postcopy: enable compress during postcopy

[Wei Yang]

This patch set tries enable compress during postcopy.

postcopy requires to place a whole host page, while migration thread migrate
memory in target page size. This makes postcopy need to collect all target
pages in one host page before placing via userfaultfd.

To enable compress during postcopy, there are two problems to solve:

    1. Random order for target page arrival
    2. Target pages in one host page arrives without interrupt by target
       page from other host page

The first one is handled by counting the number of target pages arrived
instead of the last target page arrived.

The second one is handled by:

    1. Flush compress thread for each host page
    2. Wait for decompress thread for before placing host page

With the combination of these two changes, compress is enabled during
postcopy.

---
v2:
     * use uintptr_t to calculate place_dest
     * check target pages belongs to the same host page

Wei Yang (6):
  migration/postcopy: reduce memset when it is zero page and
    matches_target_page_size
  migration/postcopy: wait for decompress thread in precopy
  migration/postcopy: count target page number to decide the
    place_needed
  migration/postcopy: set all_zero to true on the first target page
  migration/postcopy: enable random order target page arrival
  migration/postcopy: enable compress during postcopy

 migration/migration.c | 11 -------
 migration/ram.c       | 67 +++++++++++++++++++++++++++++++++----------
 2 files changed, 52 insertions(+), 26 deletions(-)

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2.17.1