Re: [PATCH] kswapd fix & logic improvement

Benjamin C.R. LaHaise (
Fri, 6 Mar 1998 04:06:22 -0500 =?ISO-8859-1?Q?(U=01?=)


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...


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