Commit d05de9e3 authored by Keqian Zhu's avatar Keqian Zhu Committed by Juan Quintela
Browse files

migration: Optimization about wait-unplug migration state 



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: default avatarKeqian Zhu <zhukeqian1@huawei.com>
Reviewed-by: default avatarJuan Quintela <quintela@redhat.com>
Tested-by: default avatarJens Freimann <jfreimann@redhat.com>
Reviewed-by: default avatarJens Freimann <jfreimann@redhat.com>
Signed-off-by: default avatarJuan Quintela <quintela@redhat.com>
parent 8958338b

migration/migration.c

+1 −1
Original line number Diff line number Diff line
@@ -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);

migration/savevm.c

+3 −21
Original line number Diff line number Diff line
@@ -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 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 true;

        }

    }



    return n > 0;

    return false;

}



void qemu_savevm_state_setup(QEMUFile *f)

migration/savevm.h

+0 −1
Original line number Diff line number Diff line
@@ -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);