TCP Reassembly Issues

George Mitchell george+freebsd at m5p.com
Fri Nov 25 18:05:13 UTC 2011


On 11/24/11 21:00, Jeremy Chadwick wrote:
>[...]
> If none of this solves the problem, then I consider this a priority 0
> blocker (read: "all hands on deck") issue with the IP stack in FreeBSD
> 9.x and will need immediate attention.
>
> I would strongly recommend a developer or clueful end-user begin
> tracking down who committed all of these bits and CC them into the
> thread.  I would start by looking who implemented the
> net.inet.tcp.reass.cursegments sysctl, because that isn't in RELENG_8 at
> all.
>

I've tried out the 9.0 release candidates, and what I notice is that for
a few minutes after the system starts, I get wonderful NFS read
throughput (7+ MB/s over a 100 megabit interface) -- more than twice as
fast as 7.n or 8.n on the same hardware -- quickly degrading to abysmal
(less than 0.5 MB/s).  Is this possibly related to the problem under
discussion?                                          -- George Mitchell

P.S. A lot of other 9.0 features look very nice indeed!


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