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SubjectQuestion about i820 chipset.
Hi Alan,

I have some small questions...

Have you ever tried a motherboard with i820 chipset and two NIC's?
I have a Asus P3C-D here (dual pIII 800 with 256MB rimm) and a D-Link
DFE570-TX NIC (quad DECchip 21143 behind a DECchip 21152 pci bridge).

The problem I'm seeing is extremely crappy pci performance.
With one of the NIC's active I see no real problems but when two NIC's are
active at the same time all hell breaks loose :(

if I generate traffic out via 2 NIC's at the same time I'd expect to get
about 2 x 100Mbit/s but in reality I get 2 x 25Mbit/s with this
motherboard. and with 3 NIC's active I get about 3 x 15-20Mbit/s.

I tried replacing the motherboard with an old SMP board based on the 440bx
chipset (cpus underclocked to 600MHz) and then I can easily get 3 x
100Mbit/s with 25-30% cpu used in the machine.

So my question is, have you ever seen such pci issues? I've tried all
BIOS settings I could find and a lot of diffrent kernels. I've also tried
the vanilla tulip-driver and the NAPI'fied one (which I have been helping
to test) and both show the exact same performanceproblems.

I tried routing a lot of packets and it started dropping a lot of packets
when the cpu was only 75% used according to both vmstat and cyclesoak
(with an UP kernel). A profile shows that default_idle gets about 25% of
the time. I assume the kernel is waiting for the pci bus.

And the last question, if you have the hardware, would you mind testing
something similar on the Asus A7M266-D? We've been thinking of getting a
few of these boards to replace the crappy i820 ones.

I saw that you included a patch for MPS 1.4 in -pre9-ac1, was this the
same patch you were talking about earlier and does it work?

/Martin

Never argue with an idiot. They drag you down to their level, then beat you with experience.


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