Re: Socket problem in Fedora Core 2

[Bob Chiodini <rchiodin@xxxxxxxxxxxxx>]

On Thu, 2005-09-08 at 22:16 +0200, Andreas Storm wrote: 
> Hi again Bob,
> 
> I used the /sbin/sysctl message to increase the value.
> Set it to net.ipv4.tcp_max_orphans = 64000
> 
> Thing is that I still get the same problem. After
> ~20k TCP connections dmesg reports "Out of socket memory"
> 
> Do you have any other ideas?
> 
> Thanks,
> /Andreas
> 
> 
> -----Original Message-----
> From: "Andreas Storm" <powerout@xxxxxxx>
> To: fedora-list@xxxxxxxxxx
> Date: Thu, 08 Sep 2005 18:53:29 +0200
> Subject: Re: Re: Socket problem in Fedora Core 2
> 
> Hi Bob,
> 
> Sorry for top-posting. Thanks for the help, will
> try it out right away.
> 
> /Andreas
> 
> -----Original Message-----
> From: Bob Chiodini <rchiodin@xxxxxxxxxxxxx>
> To: For users of Fedora Core releases <fedora-list@xxxxxxxxxx>
> Date: Thu, 08 Sep 2005 10:17:08 -0400
> Subject: Re: Socket problem in Fedora Core 2
> 
> On Thu, 2005-09-08 at 10:10 -0400, Bob Chiodini wrote:
> > On Thu, 2005-09-08 at 14:58 +0200, Andreas Storm wrote:
> > > Hi,
> > > 
> > > My setup: Fedora Core 2 with 2.6.10-1.771_FC2smp kernel.
> > > 
> > > I'm currently developing a simulator for load testing
> > > which needs to handle around 40-50K connections. A mixture of TCP and UDP.
> > > 
> > > I changed the amount of file descriptors to 64000
> > > with ulimit -n 64000 as root.
> > > 
> > > But when I run and reach around 27000 TCP connections
> > > my application stops and dmesg writes the following:
> > > 
> > > "out of socket memory" several times.
> > > 
> > > I wonder what is the problem and how it can be fixed. Didn't have any luck at the mail archive or google.
> > > 
> 
> > > Any help appreciated.
> > > 
> > > Br,
> > > /Andreas
> > > 
> > > 
> > > 
> > 
> > Andreas,
> > 
> > I found the "out of socket memory" in tcp_timer.c.  The implication that
> > the sysctl variable net.ipv4.tcp_max_orphans controls the limit (among
> > other things).  On FC3 this is set to 65536.  What is it in FC2?
> > 
> > Bob...
> > 
> 
> Andreas,
> 
> I found an FC2 machine:
> 
> /sbin/sysctl net.ipv4.tcp_max_orphans
> net.ipv4.tcp_max_orphans = 16384
> 
> You might try bumping that number up.
> 
> Bob...
> 

Andreas,

There are couple of other potential candidates.  Try /sbin/sysctl -a |
sort to see the variables that are settable.  net.ipv4.tcp_mem is a
likely one.  I believe you must quote the list of values.  In FC3 the
values are 4 times larger than in FC2:

196608  262144  393216

To change your system to these values use:

/sbin/sysctl -w net.ipv4.tcp_mem='196608  262144  393216'

To make these permanent add the changes to /etc/sysctl.conf.

Bob...