I've been following the kernel digest, and searching for solutions to this
problem, and several recent posts are suggesting that the NIC driver is at
fault, or that its just a debugging message which will go away in 2.2. I
get 1/3 the ftp transfer rate with 2.1.125 and 2.1.127-pre7 compared to
2.0.33. My problem occurs using ppp and serial drivers; so I would think
the only common thing between my problem and the others is the tcp_ipv4
code. Since I've got an old tired serial interface, my guess is that
interrupts aren't being serviced fast enough?
Umm.... I'm using a Linux 2.1.126 kernel with a V.90 56kbps modem card,
and I'm getting 4-4.5kbps FTP transfer rates using PPP and the serial
driver via the PCMCIA interface. So it's not quite that simple....
Are you using autoirq with setserial? That broke for some people when
we regularized the IRQ interface, but testing for that is very hard,
becuase it's dependent on the vagrancies of random UART's chips,
particularly the non-standard (i.e., non-National Semiconductor) UARTs.
So if you're using autoirq, and it failed, the irq would be set to 0,
and that would certainly explain the lousy performance. I very, very,
very, strongly recommend that people NOT using autoirq. Trying to do
automatic IRQ detection with the ISA bus is dicecy at best, because the
ISA bus really isn't designed for it.....
I recommend that people use setserial and manually set the irq to the
correct value. In the latest (just released) setserial, there's a much
nicer way of doin this which uses a file /etc/serial.conf as a place for
configuring the IRQ information.
- Ted
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