AW2: [vortex] 3c59x slow; debug=5 removes the error; why?

[Christian Ostheimer]

addendum to previous message: kernel 2.6.6 seems to have improved the speed
> Von: Bogdan Costescu, 18. Mai 2004 13:02
> On Sat, 15 May 2004, Christian Ostheimer wrote:
>
> > case 1): insmod 3c59x
> >   30-80kB/s; 30% overrun errors
>
> Given the direction of the transfer, I assume that you are talking
> about the Rx overruns that ifconfig displays. Rx overruns appear when
> the host is too slow for the incoming data, which leads to filling up
> all Rx buffers - at this point the card cannot receive any more
> packets and everyhting is dropped. This is not a normal situation and
> based on the description of your notebook it should be powerful enough
> to handle 100Mbit/s.
>
> > case 2): insmod 3c59x debug=5
> >   6-10MB/s; 0.02% overruns
>
> This is a bit more normal, however the presence of overruns is still
> not a good sign. Furthermore, increasing "debug" leads to lower
> performance of the driver as time is spent on the calls to "printk",
> which should not increase transfer speed... So it's something to do
> with the timing and coupled with:
>
> > PCI: Found IRQ 11 for device 0000:02:00.0
> > PCI: Sharing IRQ 11 with 0000:00:1f.1
>
> ... makes me believe that it has something to do with the interrupt
> sharing. What is the device that is sharing the IRQ with the 3Com NIC?
> Is is possible to disable this device in BIOS and see if the problem
> dissapears ?
not with a dell bios... - I checked with windows xp: the interrupts are
shared the same way: grafics adapter (and usb and cardbus, both unused
during tests)
share irq 11 with the nic :-(
However I tried with warftpd and xp and got full speed (that is 8-10 MB/s;
uploading with the same client as I did with linux)

I do not believe that it is the new kernel code, because 2.6.3 and 2.4.21
show the same behaviour
>
> > downloading from notebook to pc and file transfers by scp in both
> > directions give full speed
>
> Hmm, only Rx interrupts seem to be affected...
when switching between rx and tx (scp works in *both* directions)
>
> > Comparing tx and rx packets shows that ftp has 0.7MB tx packets with
> > 33 MB rx and scp has only 0.2 MB tx with 33 MB rx.
>
> That's probably because of the TCP retransmissions.
>
Thanks for reading through my logfiles.

Christian Ostheimer