[Drbd-dev] Huge latency issue with 8.2.6

[Graham, Simon]

> > Conclusion 2 -- the problem here has to do with the time is takes
the
> secondary to send the TCP ACK.
> 
> in git on the way to 8.2.7, we added the TCP_NODELAY socket option,
> 

I saw that and it's goodness BUT this controls the Nagle algorithm and
NOT the Ack Delay timer - you need (I believe) TCP_QUICKACK as well (or
a global change on the connection to lower the ack delay but I think
that would be bad - the nice thing about TCP_QUICKACK is that it's a one
time setting that causes pending acks to be sent right now but does not
change the normal ack delay).

Simon