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Re: [lwip-users] tcp client using sockets

From: Sathya Thammanur
Subject: Re: [lwip-users] tcp client using sockets
Date: Mon, 17 Apr 2006 07:16:27 -0700

Hi Kyle,
There should not be any requirements on the sequence of read's and write's to be ordered. However, as far as I know, the socket calls for read and write are blocking. I dont think lwip supports non-blocking sockets unless someone can correct me on this. Can this be a reason for the behaviour that you are seeing?


On 4/15/06, kyle treleaven <address@hidden> wrote:
I'm building a tcp client using the sockets api in lwip.  Am running
on xilinx port to the ppc of virtex fpga.  I base my client on the
echo server example, and I've posted here before about the same thing.
I changed the code incrementally, very slowly, testing the
performance at each phase.  Basically, the client broke at the very
last step.  Up until that point I had been testing the client against
a very simple echo server.  I'd send it an initial byte representing
the number of times I wanted it to relay a phrase back and forth with
the client, and then I would receive, reply, receive, reply and so
on... ie. write(), read(), write(), read(), write(), read().... in an
arbitrarily long sequence.

The client breaks when i no longer do things in that exact order:
write(), read(), write(), read()...  That is to say I may still
receive the data, but only after a number of retransmit pushes from
the server, and with a delay of 10-20 seconds, which is clearly
unacceptable.  It's as though some interrupt or polling loop isn't
firing correctly, but all of the OS and lwip setup code remains
exactly as it was in the server example.  Has anybody else encountered


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