Re: VM tuning for Linux routers

[Francois Romieu <romieu@cogenit.fr>]

Bernd Eckenfels <ecki@lina.inka.de> :
[...]
> You can increase the reserved free memory (not sure where to do this in
> 2.4.x). This is important, cause network memory requests are usually within
> interrupt handlers and therefore no paging can occur. You can play a bit

This reserve isn't dedicated to networking alas.

[...]
> > However you can increase the length of the Rx/Tx rings on the 100Mb/s side 
> > and tune the pci latency timers (depends on the hardware fifo size). 
> 
> Increasing rx/rx rings is not a particular good idea cause it slows down
> TCPs adaption to network congestion and router overload.

Think about forwarding between GigaE and FastE. Think about overflow and
bad irq latency. I wouldn't cut buffering at l2 as it averages the peaks. 
Different trade-offs make sense of course.

-- 
Ueimor