Improve modem connection under heavy disk activity

Hi,

My modem internet connection suffers badly under heavy disk activity - it is practically impossible to complete any connection and data flow stalls. I presume that this is due to data being dropped while the kernel is busy servicing the disk io. Perhaps this is inevitable, but perhaps someone knows a tweak that can improve responsiveness - maybe prioritise the processes buttociated with the modem-serial port or something along those lines.

I'm using a 56k modem which I can only get to connect at a maximum of 50666. That's a different issue though - I think it's just an inferior brand. My computer is a P4 1600Mhz with 768Mb RAM and the serial port has a 16550A UART. At the moment I'm using kpppd to connect (which ultimately uses pppd) although I also have chat scripts and provider settings so that I can invoke pppd directly with pon and poff.

My kernel is 2.6.11-gentoo-r6 and I'm using a Gentoo distro.

Under kpppd the pppd daemon is invoked as follows: debug

I compiled the three different io schedulers as modules when compiling the kernel but I'm not sure how to go about using them and don't know if any of them will help my problem - anyone got any experience with these?

Any suggestions welcome. Let me know if more information is necessary.