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Fwd: tcp write performance testing

A quick update on tcp performance after the recent code refactoring:

TCP read speeds have gone down from about 1 Gb/s between VMs on the
same host to about 450 Mb/s.  It looks like this is because of a flow
control / pkt dispatch problem.  TCP write seems to have a more
serious problem that it is sending pkts outside the available window -
these pkts are dropped as expected and then the stack spends most of
the time re-xmiting and recovering from the losses.  It looks like the
write calls succeed instead of failing or blocking when there is no
window available.

So if you are using it, expect TCP to be very fragile for now.  Also
it looks like DHCP is not working and there is a small race condition
in ARP.




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