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migration: Disallow postcopy preempt to be used with compress

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The preempt mode requires the capability to assign channel for each of the
page, while the compression logic will currently assign pages to different
compress thread/local-channel so potentially they're incompatible.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This commit is contained in:
Peter Xu 2022-10-04 14:24:28 -04:00 committed by Juan Quintela
parent f5816b5c86
commit afed4273b5
1 changed files with 11 additions and 0 deletions
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11
migration/migration.c
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@ -1337,6 +1337,17 @@ static bool migrate_caps_check(bool *cap_list,
error_setg(errp, "Postcopy preempt requires postcopy-ram");
return false;
}
/*
* Preempt mode requires urgent pages to be sent in separate
* channel, OTOH compression logic will disorder all pages into
* different compression channels, which is not compatible with the
* preempt assumptions on channel assignments.
*/
if (cap_list[MIGRATION_CAPABILITY_COMPRESS]) {
error_setg(errp, "Postcopy preempt not compatible with compress");
return false;
}
}
return true;