I'm not convinced it's the domain of an IO scheduler to be
involved,
rather than it being explicit UX intended by the desktop environment.
Seems to me the desktop environment is in a better position to know
what users expect.
Well wouldn't bfq just be enforcing the bandwidth weights, if any, that were
explicitly set in the various groups? If something is already creating and modifying
control groups, then that something should have total control over setting the bandwidth
weights. It's not obvious to me how the IO scheduler would be bypassing or otherwise
ignoring whatever manages control groups.
It's also not clear to me how anything except an IO scheduler would be able to
directly control how device bandwidth is shared.