>
> On Wed, 10 Oct 2007, Jupe wrote:
>
> > Hi,
> >
> > I have written an ethernet driver for an ARM based board.
> > Linux version: 2.6.20.1
> >
> > Ping is working fine.
> >
> > I have written a test server/client application using socket programming
> > (TCP).
> > After the connection is setup the server sends a file to the client.
> >
> > When I run server on PC and client on ARM board it works without any
> > problem.
> >
> > BUT if I run server on ARM board and client on PC, it works for some
> > time and
> > then the speed is drastically reduced. (I am sending 4k of data each
> > time.
> > after 50 sends it reduces its speed. This happens always.)
> >
> > I did some debugging and found that after 50 sends, tcp_sendmsg() is not
> > being
> > called at the same frequency before slowdown. Also when my driver
> > ether_tx seems to
> > be working fine.
> >
> > But still i am not able to get the reason for this behaviour. Can
> > anyone give hints as to
> > why this is happening?
> >
> >
> > Regards
> > Jupe
> >
> > --
> > Jupe
> >
jupejupe@rushpost.com
> >
> > --
> >
http://www.fastmail.fm - mmm... Fastmail...
>
> First, does your TCP/IP test application work okay on
> a Linux machine that does not use your new driver?
>
> That's the first thing to test.
>
> Next, is auto-negotiation working correctly in your
> driver? If you don't have auto-negotiation, have you
> set the Ethernet parameters correctly so that BOTH
> the server and the client use either full-duplex, or
> half-duplex, without mixing them up?
>
> Next, make sure that you are properly handling
> transmit retries (handling all possible errors)
> in your driver. The transmitter does not want
> to drop packets if there is no room in the
> device, only the receiver should drop packets
> if there are no buffers. You do not want
> the TCP/IP replacement algorithm to request
> missing packets because this slows everything
> down. Again, in the transmitter section
> of your driver, consider data precious.
>
>
> Cheers,
> Dick Johnson
> Penguin : Linux version 2.6.16.24 on an i686 machine (5592.59 BogoMips).
> My book :
http://www.AbominableFirebug.com/
> _
>
>
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