Re: [PATCH] kswapd fix & logic improvement

["Benjamin C.R. LaHaise" <blah@kvack.org>]

Hello!

On Wed, 4 Mar 1998, Pavel Machek wrote:
...
> > Not only that, but the network activity X induces puts additional stress
> > on an already low-memory system by allocating lots of unswappable memory.
> > When might we see Pavel's patches to the networking stack meant to get
> > swapping over TCP working, but I think they'll really help stability on 
> > systems with low-memory and busy networks, get integrated?
> 
> Sorry? My patches are usable only if you are trying to swap over
> network. They will not help on low-memory systems, unless that systems
> also lack hard-drives. It is usually much better to swap onto local
> drive than over network.

If they're setup the way I think they are, you're mistaken. ;-)  I'm
thinking of the pathelogical case where the system is thrown into a state
where atomic memory consumption is occurring faster than the system can
free up memory.  This could occur on a system with, say 100Mbps ethernet
and a low-end IDE drive (~5-7MBps peak) if we're using TCP with large
windows and have a *large* number of sockets open and receiving data. 
Incoming packets could consume up to 10MB of GFP_ATOMIC memory per second
- ouch!  With your patch, once we hit a danger zone, the system starts
dropping network packets, right?  That way there will still be enough
memory for allocating buffer heads and such to swap out as nescessary... 

		-ben