[Drbd-dev] Huge latency issue with 8.2.6

Lars Ellenberg lars.ellenberg at linbit.com
Sat Aug 16 18:55:18 CEST 2008

On Sat, Aug 16, 2008 at 12:44:33PM -0400, Graham, Simon wrote:
> > > 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).

I had the impression that the NODELAY would imply QUICKACK behaviour,
and together witht the CORK and UNCORK should do the trick.
but I'm happy to be enlightened.

will commit a slightly modified verion of your quickack soonish.


: Lars Ellenberg                
: LINBIT HA-Solutions GmbH
: DRBD®/HA support and consulting    http://www.linbit.com

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