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migration: Optimization about wait-unplug migration state

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qemu_savevm_nr_failover_devices() is originally designed to
get the number of failover devices, but it actually returns
the number of "unplug-pending" failover devices now. Moreover,
what drives migration state to wait-unplug should be the number
of "unplug-pending" failover devices, not all failover devices.

We can also notice that qemu_savevm_state_guest_unplug_pending()
and qemu_savevm_nr_failover_devices() is equivalent almost (from
the code view). So the latter is incorrect semantically and
useless, just delete it.

In the qemu_savevm_state_guest_unplug_pending(), once hit a
unplug-pending failover device, then it can return true right
now to save cpu time.

Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Tested-by: Jens Freimann <jfreimann@redhat.com>
Reviewed-by: Jens Freimann <jfreimann@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This commit is contained in:
Keqian Zhu 2020-02-04 13:08:41 +08:00 • committed by Juan Quintela
parent 8958338b10
commit d05de9e39a
3 changed files with 4 additions and 23 deletions
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2
migration/migration.c
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@ -3341,7 +3341,7 @@ static void *migration_thread(void *opaque)
qemu_savevm_state_setup(s->to_dst_file);
if (qemu_savevm_nr_failover_devices()) {
if (qemu_savevm_state_guest_unplug_pending()) {
migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
MIGRATION_STATUS_WAIT_UNPLUG);