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sis900: eth0: NULL pointer encountered in Rx ring, skipping

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Subject: sis900: eth0: NULL pointer encountered in Rx ring, skipping
From: Lennert Buytenhek <buytenh@xxxxxxxxxxxxxx>
Date: Tue, 18 Jan 2005 11:13:58 +0100
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Hi,

I can make one of my machines, which has an on-board sis900 NIC, lose
network connectivity within seconds by doing something like
"nc -l -p 6666 > /dev/null" and then blasting some data towards it.  When
this happens, syslog fills up with these messages:

        eth0: NULL pointer encountered in Rx ring, skipping

It seems like the driver+NIC combo doesn't handle any kind of load very
well in general -- whenever it receives more than just a few tens of
packets per second, the machine's ping time turns rather awful:  (Two
machines on 100Mb/s with an el-cheapo 8-port 100Mb/s switch between
them.  Other machines on the same switch don't show any of the same
problems.)

        64 bytes from 10.0.0.4: icmp_seq=212 ttl=64 time=128 ms
        64 bytes from 10.0.0.4: icmp_seq=213 ttl=64 time=124 ms
        64 bytes from 10.0.0.4: icmp_seq=214 ttl=64 time=119 ms
        64 bytes from 10.0.0.4: icmp_seq=215 ttl=64 time=124 ms

When it locks up, 'ifconfig eth0 down up' suffices to make it come back
to life.  I haven't checked whether it's just RX that stops working or
whether it's both RX and TX.

Any ideas?  This is on the Fedora Core 3 update kernel, 2.6.10-based.


cheers,
Lennert

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