On 19/05/2021 16:28, David Sterba wrote:

On Wed, May 19, 2021 at 06:53:54AM +0000, Johannes Thumshirn wrote:

quoted

On 18/05/2021 16:52, David Sterba wrote:
I wonder if this interface would make sense for limiting balance
bandwidth as well?

Balance is not contained to one device, so this makes the scrub case
easy. For balance there are data and metadata involved, both read and
write accross several threads so this is really something that the
cgroups io controler is supposed to do.

For a user initiated balance a cgroups io controller would work well, yes.
But for having a QoS mechanism to decide when it's a good time to rebalance
one or more block groups, i.e. with a zoned file system or when we switch
to auto-balance in the future I'm not sure if cgroups would help us much
in this case.

But this can be my lack of knowledge as well.