[pve-devel] [PATCH V2] - fix setting migration parameters

[Dietmar Maurer]

>  - move migration speed/downtime from QemuServer vm_start to
>    QemuMigrate phase2

what is the advantage?

>  - lower default migration downtime value to 0

We do not want that, because this is known to cause long wait times on busy VMs.

> ---
>  PVE/QemuMigrate.pm |   30 ++++++++++++++++++++++++++----
>  PVE/QemuServer.pm  |   17 +----------------
>  2 files changed, 27 insertions(+), 20 deletions(-)
> 
> diff --git a/PVE/QemuMigrate.pm b/PVE/QemuMigrate.pm index
> 0711681..af8813c 100644
> --- a/PVE/QemuMigrate.pm
> +++ b/PVE/QemuMigrate.pm
> @@ -323,24 +323,46 @@ sub phase2 {
>      $self->{tunnel} = $self->fork_tunnel($self->{nodeip}, $lport, $rport);
> 
>      $self->log('info', "starting online/live migration on port $lport");
> -    # start migration
> 
> -    my $start = time();
> +    # load_defaults
> +    my $defaults = PVE::QemuServer::load_defaults();
> +
> +    # always set migrate speed (overwrite kvm default of 32m)
> +    # we set a very hight default of 8192m which is basically unlimited
> +    my $migrate_speed = $defaults->{migrate_speed} || 8192;
> +    $migrate_speed = $conf->{migrate_speed} || $migrate_speed;
> +    $migrate_speed = $migrate_speed * 1048576;

This makes sure that $migrate_speed is an integer.

> +    $self->log('info', "migrate_set_speed: $migrate_speed");
> +    eval {
> +        # *1 ensures that JSON module convert the value to number
> +        PVE::QemuServer::vm_mon_cmd_nocheck($vmid,
> "migrate_set_speed", value => $migrate_speed*1);

so $migrate_speed*1 is not needed here.

> +    };
> +    $self->log('info', "migrate_set_speed error: $@") if $@;
> +
> +    my $migrate_downtime = $defaults->{migrate_downtime};
> +    $migrate_downtime = $conf->{migrate_downtime} if defined($conf-
> >{migrate_downtime});
> +    $self->log('info', "migrate_set_downtime: $migrate_downtime");
> +    eval {
> +        # *1 ensures that JSON module convert the value to number
> +        PVE::QemuServer::vm_mon_cmd_nocheck($vmid,
> "migrate_set_downtime", value => $migrate_downtime*1);

Please use:

value => int($migrate_downtime)

Or what is the advantage of '*1'?


> +    # start migration
> +    my $start = time();

what is this?

>      eval {
>          PVE::QemuServer::vm_mon_cmd_nocheck($vmid, "migrate", uri =>
> "tcp:localhost:$lport");
>      };
> diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm index
> 1d4c275..bb7fd16 100644
> --- a/PVE/QemuServer.pm
> +++ b/PVE/QemuServer.pm
> @@ -385,7 +385,7 @@ EODESCR
>  	type => 'integer',
>  	description => "Set maximum tolerated downtime (in seconds) for
> migrations.",
>  	minimum => 0,
> -	default => 1,
> +	default => 0,
>      },
>      cdrom => {
>  	optional => 1,
> @@ -2979,21 +2979,6 @@ sub vm_start {
>  	    warn $@ if $@;
>  	}
> 
> -	# always set migrate speed (overwrite kvm default of 32m)
> -	# we set a very hight default of 8192m which is basically unlimited
> -	my $migrate_speed = $defaults->{migrate_speed} || 8192;
> -	$migrate_speed = $conf->{migrate_speed} || $migrate_speed;
> -	$migrate_speed = $migrate_speed * 1048576;
> -	eval {
> -	    vm_mon_cmd_nocheck($vmid, "migrate_set_speed", value =>
> $migrate_speed);
> -	};
> -
> -	my $migrate_downtime = $defaults->{migrate_downtime};
> -	$migrate_downtime = $conf->{migrate_downtime} if defined($conf-
> >{migrate_downtime});
> -	if (defined($migrate_downtime)) {
> -	    eval { vm_mon_cmd_nocheck($vmid, "migrate_set_downtime",
> value => $migrate_downtime); };
> -	}
> -
>  	if($migratedfrom) {
>  	    my $capabilities = {};
>  	    $capabilities->{capability} =  "xbzrle";
> --
> 1.7.10.4
> 
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