openssh unix dev - Oct 2009 - ControlMaster and packet stuffing

When I'm running interactive ssh session which is ControlMaster and I run
scp
or sftp to same host, creating another channel, it seems that ssh is stuffing
the packets together exceeding MTU.

I've for years ran QoS where I prioritize small packets, as it is clean and
easy way to guarantee low latency to pretty much all you care for.
Unfortunately ControlMaster packet stuffing breaks this, my interactive packets
are not small anymore for the duration of scp/sftp and receive best effort
treatment
making my interactive session extremely laggy.

Is there particular need to combine interactive packets with MTU sized data
packets? In what type of situation is the current behaviour desired?

Thanks,
-- 
  ++ytti

> When I'm running interactive ssh session which is ControlMaster and I
run scp
> or sftp to same host, creating another channel, it seems that ssh is
stuffing
> the packets together exceeding MTU.
It seems likely that I got confused by looking tshark, seeing box sending
bigger packets than MTU, but that was likely due to XEN NIC offering
large-segment-offload.
So this may be expected behaviour with no obvious workaround, other than
not using ControlMaster when doing both interactive and sftp/scp to same
host.

-- 
  ++ytti