Ethernet, kernel bug/weakness

Harald Welte laforge at
Fri Mar 8 19:03:41 EST 2002

On Thu, Mar 07, 2002 at 03:50:04PM -0500, Ruhland, Paul wrote:
> Effect:
> --
> Once the ethernet traffic goes above the critical point described above, all
> cpu cycles are spent servicing the ethernet traffic.

This is a common problem, also found with gigabit ethernet and large x86
boxes (or 100MBit and medium x86 boxes), as soon as you start shooting at them
with foll wire speed 20bytes IP packets.

It is well-known and about two years ago Jamal Hadi Selim and others were
solving the problem for a couple of example ethernet chips by using IRQ
mitigation.  This way the packets will get dropped on the network card

Seems like your driver isn't using this strategy for some strange reason.

Alternatively you can also try to detect high load within the driver and
switch to polling mode - this also has been implemented successfully in
some drivers, IIRC.

> Paul Ruhland

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- Harald Welte / laforge at     
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