From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH] socket: increase default maximum listen queue length
Date: Sun, 20 Mar 2011 12:55:44 +0100
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To: Hagen Paul Pfeifer <hagen@jauu.net>
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Le dimanche 20 mars 2011 =C3=A0 12:39 +0100, Hagen Paul Pfeifer a =C3=A9=
crit :
> * Eric Dumazet | 2011-03-20 09:30:17 [+0100]:
>=20
> >Hmm, real problem is not the 'maximum queue value', but the minimum =
one.
> >
> >If application says : listen(fd, 10), you are stuck.
> >
> >128 or 256 is way too small on some servers, where admin can tune
> >in /etc/sysctl.conf :
> >
> >net.core.somaxconn =3D 8192
> >net.ipv4.tcp_max_syn_backlog =3D 8192
> >
> >But application also needs to use : listen(fd, 8192)
>=20
> I know Eric, I wrote the patch. ;-) The used naming goes like this:
>=20
> The system limits (somaxconn & tcp_max_syn_backlog) specify a _maximu=
m_, the
> user cannot exceed this limit with listen(2). The backlog argument fo=
r listen
> on the other hand specify a _minimum_. But the patch increased the de=
fault
> maximum, therefore I named it in this way.


I am not sure you understood what I said.

Even if you change kernel limits, many applications still use low
limits : listen(fd, 8)

I remember some other OS (was it HPUX or Solaris...) had a minimum
limit : Even if application said 8, an admin could impose a 256 value
for example.

=46rankly, I believe somaxconn should be a default enforcement, that a
particular protocol could override.

TCP sockets for example should only enforce tcp_max_syn_backlog limit,
not the somaxconn & tcp_max_syn_backlog.