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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
View File

@ -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);

24
migration/savevm.c
View File

@ -1140,36 +1140,18 @@ void qemu_savevm_state_header(QEMUFile *f)
}
}
int qemu_savevm_nr_failover_devices(void)
bool qemu_savevm_state_guest_unplug_pending(void)
{
SaveStateEntry *se;
int n = 0;
QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
if (se->vmsd && se->vmsd->dev_unplug_pending &&
se->vmsd->dev_unplug_pending(se->opaque)) {
n++;
return true;
}
}
return n;
}
bool qemu_savevm_state_guest_unplug_pending(void)
{
SaveStateEntry *se;
int n = 0;
QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
if (!se->vmsd || !se->vmsd->dev_unplug_pending) {
continue;
}
if (se->vmsd->dev_unplug_pending(se->opaque)) {
n++;
}
}
return n > 0;
return false;
}
void qemu_savevm_state_setup(QEMUFile *f)

1
migration/savevm.h
View File

@ -31,7 +31,6 @@
bool qemu_savevm_state_blocked(Error **errp);
void qemu_savevm_state_setup(QEMUFile *f);
int qemu_savevm_nr_failover_devices(void);
bool qemu_savevm_state_guest_unplug_pending(void);
int qemu_savevm_state_resume_prepare(MigrationState *s);
void qemu_savevm_state_header(QEMUFile *f);