Re: Break 2.4 VM in five easy steps

[Mike Galbraith <mikeg@wen-online.de>]

On 6 Jun 2001, Eric W. Biederman wrote:

> Derek Glidden <dglidden@illusionary.com> writes:
>
>
> > The problem I reported is not that 2.4 uses huge amounts of swap but
> > that trying to recover that swap off of disk under 2.4 can leave the
> > machine in an entirely unresponsive state, while 2.2 handles identical
> > situations gracefully.
> >
>
> The interesting thing from other reports is that it appears to be kswapd
> using up CPU resources.  Not the swapout code at all.  So it appears
> to be a fundamental VM issue.  And calling swapoff is just a good way
> to trigger it.
>
> If you could confirm this by calling swapoff sometime other than at
> reboot time.  That might help.  Say by running top on the console.

The thing goes comatose here too. SCHED_RR vmstat doesn't run, console
switch is nogo...

After running his memory hog, swapoff took 18 seconds.  I hacked a
bleeder valve for dead swap pages, and it dropped to 4 seconds.. still
utterly comatose for those 4 seconds though.

	-Mike

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