TCP Reassembly Issues

[Ivan Voras]

On 24.11.2011. 8:02, Kris Bauer wrote:
> Hello,
>
> I am currently experiencing an issue with FreeBSD 9.0-RC2 r227852 where the
> net.inet.tcp.reass.curesegments value is constantly increasing (and not
> descreasing when there is nominal traffic with the box).  It is causing tcp
> slowdowns as described with kern/155407:
>
> Exhausted net.inet.tcp.reass.maxsegments block recovering tcp session (for
> this socket and any other socket waiting for retransmited packets). After
> exhausted net.inet.tcp.reass.maxsegments allocation new entry in tcp_reass
> failed (for this socket and any other socket waiting for retransmited
> packets).
>
> I have increased the reass.maxsegments value to 16384 to temporarily avoid
> the problem, but the cursegments number keeps rising and it seems it will
> occur again.
>
> Is this an issue that anyone else has seen?  I can provide more information
> if need be.

Is your configuration different than the default in some way? Do you use 
a firewall? Multithreaded netisr? One of the new TCP congestion control 
modules?