This could also be interesting. It means canceling the balance in
progress; waiting some time; and then cancelling it again to get
results to return.

# perf stat -B btrfs balance start /

## Again, single device example, balancing at expected performance.
http://fpaste.org/320562/55071438/

I didn't try this but, it looks like it'd be a variation on the above,
attaching to a running balance:

# perf stat -B -p <pidforbalance> sleep 60

Anyway...

Chris Murphy