[ECOS] dropped UDP packets on 8270 PowerPC board

[Andrew Lunn]

On Mon, Jan 23, 2006 at 10:19:43AM -0500, Paul Randall wrote:
> Hi all,
> 
> I have been having a problem with UDP packets being dropped on a 
> Freescale MPC8270 board we developed based on the A&M Rattler 8280 PCI 
> board.
> 
> I have added sequence numbers to each UDP packet being transmitted to 
> the board.  The application running on the board prints an error message 
> when it detects a missing sequence number.  If the board is only 
> receiving packets and not transmitting them, I don't get any missing 
> packets, even up to a bitrate of 5 Mbit/sec.  However when the board has 
> to transmit data, I start to see missing sequence numbers in the 
> received data.
> 
> I'm not sure where the packets are being dropped.  I tried adding debug 
> messages to the ethernet driver, but I'm not seeing anything so I assume 
> the packets are being dropped in the TCP/IP stack.
> 
> Has anyone seen this problem or know how I can find out where the 
> packets are being dropped?

What is the CPU load? It could just be the CPU has too much to do. The
socket code will only buffer so many packets for "userspace" and after
that it will drop packets.

So if udpstat.udps_fullsock is getting incremented. This would mean
your application is not reading the UDP messages fast enough.

        Andrew

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