high Traffic setup problem, module status don't deliver data

[Valentin V. Bartenev]

On Tuesday 11 February 2014 16:44:57 Aleksandar Lazic wrote:
> 
> Am 11-02-2014 16:28, schrieb Valentin V. Bartenev:
> > On Tuesday 11 February 2014 19:06:37 Maxim Dounin wrote:
> >> Hello!
> >> 
> >> On Tue, Feb 11, 2014 at 06:16:48PM +0400, Valentin V. Bartenev wrote:
> >> 
> >> > On Tuesday 11 February 2014 18:06:38 Maxim Dounin wrote:
> >> > [..]
> >> > > > >(As for backlog size, I usually set it to something big enough to
> >> > > > >accomodate about 1 or 2 seconds of expected peek connection rate.
> >> > > > >That is, 1024 is good enough for about 500 connections per second.
> >> > > > >But with deferred on Linux, it looks like deferred connection are
> >> > > > >sitting in the same queue as normal ones, and this may drastically
> >> > > > >change things.)
> >> > > >
> >> > > > OK. That means with deferred I should double or divide the
> >> > > > listening value?
> >> > >
> >> > > With deferred, it looks like all (potential) deferred connection
> >> > > should be added to the value.  And it's very hard to tell how many
> >> > > there will be.
> >> > >
> >> >
> >> > Deferred connections stay in syn backlog which controlled
> >> > by tcp_max_syn_backlog.
> >> 
> >> You mean they aren't counted to listen socket's backlog, right?
> > 
> > Yes.
> > 
> >> Is there any way to see how many such connections are queued then?
> > 
> > They all stay in SYN_RECV state.  If I understand right, something
> > like this will show:
> > 
> >  # netstat -n | grep SYN_RECV | grep :80 | wc -l
> 
> We have a average from ~200 here.
> 
> Is this good/bad/not worth ?
> 

Not a problem at all, till it's noticeable lower than tcp_max_syn_backlog.

  wbr, Valentin V. Bartenev