Re: mm: critical shortage of bounce buffers

[Alan Cox]

> I've recently encountered the following message on a machine running RedHat's
> 2.4.3-12 kernel :
> 
> "mm: critical shortage of bounce buffers"
> 
> I've searched through the kernel sources, but my 'find' just can't locate this
> string anywhere.

Its in the high mem handling routines. It means the machine stalled for
a moment doing I/O because it had no memory below 1Gb to use.

> Why does this message appear (apparently during high network load with the intel
> eepro100 driver or e1000 driver). Is bounce buffers really in use on a x86
> machine with 2GB of RAM (normal smp RedHat kernel, not enterprise)??

The answer is yes. You can actually build yourself a custom none bounce
buffer 1.8GB kernel with about 2Gb of user virtual space per app. For some
applications it will perform better.