Re: [Qemu-devel] [PATCH 9/9] throttle: add name of ThrottleGroup to BlockDeviceInfo

[Alberto Garcia <berto@igalia.com>]

On Tue, Feb 24, 2015 at 09:54:13AM -0700, Eric Blake wrote:

> Questions - with this series in place, is it ever possible to have
> throttling parameters without a throttle group name?

Yes, and it will work the same as before. If the throttling parameters
are set but no group name is specified then we auto-generate one.

> When using block_set_io_throttle, is it legal to pass parameters
> (like bps_max) and a group name at the same time

Yes, you're actually supposed to do it like that.

If the group does not exist yet, it's created on the fly. If the group
name is not set, then we auto-generate one.

> and if so, what happens if there is already a throttle group by that
> name?

All members of the same group share the same ThrottleState
configuration (it's stored in the group), so when you set the
throttling parameters you set them for the whole group.

For the same reason, removing a member from the group doesn't change
the throttling parameters. But once the group is empty, it is
destroyed.

> Is there a command that can return the list of all throttle group
> names?

Not currently, but I think I can add one easily. Any suggestion for
the name of the command, and for the data that you would like it to
return?

Berto