Network problem - Gradually getting slower after time.

Jonas Moberg jonas.moberg at
Tue Nov 22 09:17:56 UTC 2005

Dear RTEMS friends,

We are in the final stage of releasing our product based on RTEMS 4.6.0,
Coldfire MCF5249
and the SMSC91C111 network controller when "suddenly" a problem has arised.
Could anybody please help or come up with ideas on what could be the
We have stripped all our application code and are running only the network
tasks having the init
task to terminate. After hours (6 - 8) of uptime the network slows down and
a "ping" reply degrades to about
2 to 4 seconds. After additional uptime (2-3 days) the "ping" reply time
down to 30 to 60 seconds but still working.
The SMSC driver is based on Ian Caddys work and has proven to be rock solid
in our application (heavy RTP VOIP traffic
plus several TCP and UDP sessions open).
We have not had any buffer exhausted problem other than that after a long
uptime the transmit buffers will run out due to
the slowdown problem. However this will recover as network load is reduced
and there is "sufficient" time to send the transmit buffers.
I still can't see (although it might be) this is a driver problem as the
network performance is excellent during the first hours of operation.
The timer tick is still ticking with a 1 ms period.
Having worked around the clock for a few days we would very much appreciate
a few good ideas.

Best Regards
Solid Software AB
Jonas Moberg

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