[libvirt] question about MigrateSetMaxDowntime

[Peter Krempa]

On 12/04/14 17:53, Jim Fehlig wrote:
> A user asked me about setting max downtime prior to migration, which I
> thought could be done similar to MigrateSetMaxSpeed.  I was surprised to
> find that it can only be set when migration is in progress
> 
> # virsh migrate-setmaxdowntime test 1000
> error: Requested operation is not valid: domain is not being migrated
> 
> Is there any reason this cannot be set prior to migration?  Max speed
> can even be set on a persistent domain that is not running. I'd be happy
> to work on a patch if the only reason is no one has needed this itch
> scratched.

qemu driver allows this already since:
commit fe808d95bf353647bb39b3bc468f5a841b5588dd
Author: Chris St. Pierre <chris.a.st.pierre at gmail.com>
Date:   Mon Sep 29 13:45:28 2014 +0000

    Allow setting migration max downtime any time

    This removes the artificial and unnecessary restriction that
    virDomainSetMaxDowntime() only be called while a migration is in
    progress.

    https://bugzilla.redhat.com/show_bug.cgi?id=1146618

    Signed-off-by: Jiri Denemark <jdenemar at redhat.com>

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 63fc83f..e873d45 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -12023,12 +12023,6 @@ qemuDomainMigrateSetMaxDowntime(virDomainPtr dom,

     priv = vm->privateData;

-    if (priv->job.asyncJob != QEMU_ASYNC_JOB_MIGRATION_OUT) {
-        virReportError(VIR_ERR_OPERATION_INVALID,
-                       "%s", _("domain is not being migrated"));
-        goto endjob;
-    }
-
     VIR_DEBUG("Setting migration downtime to %llums", downtime);
     qemuDomainObjEnterMonitor(driver, vm);
     ret = qemuMonitorSetMigrationDowntime(priv->mon, downtime);

.. so I don't see any problem doing that with XEN too.

> 
> Regards,
> Jim
> 

Peter


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