Re: the TCP MSS resource exhaustion commit

Thorsten Greiner wrote:
> 
> Hi,
> 
> I have some problems after this commit. The scenario is the
> following:
> 
> I have a JBoss Application Server running on the FreeBSD 5.2-CURRENT
> machine which connects to an Oracle database (on a Sun). On several
> occasions the connection to the database is forcefully closed and I
> see the following messages in /var/log/messages:
> 
> Jan  9 09:39:29 tybalt kernel: too many small tcp packets from
> XX.XX.XX.XX:61701, av. 108byte/packet, dropping connection
> Jan  9 09:39:35 tybalt kernel: too many small tcp packets from
> XX.XX.XX.XX:61701, av. 108byte/packet, dropping connection
> Jan  9 09:45:44 tybalt kernel: too many small tcp packets from
> XX.XX.XX.XX:61701, av. 109byte/packet, dropping connection
> 
> Is there any w/around? What are the proper settings for
> net.inet.tcp.minmss and net.inet.tcp.minmssoverload in my scenario?

You can simply increase net.inet.tcp.minmssoverload to any
higher value.  I suggest 2,000 as next step.  If set it to
0 the check will be disabled entirely.

This makes we wonder why the Oracle database server is sending
so many small packets.  Is your JBoss application doing connection
pooling (eg. multiplexing multiple SQL sessions over one tcp
session)?

The documentation for these sysctl's is on its way.

-- 
Andre


> Regards
> 
>         -Thorsten
> 
> --
> Williams and Holland's Law:
>         If enough data is collected, anything may be proven by
>         statistical methods.
> 
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