Re: Odd kswapd behaviour after suspending in 2.6.11-rc1

Nigel Cunningham
2005-01-15T10:48:35Z

Hi Nick.

On Sat, 2005-01-15 at 21:40, Nick Piggin wrote:
> Nigel Cunningham wrote:
> > Hi Nick and Bernard.
> >
> > On Sat, 2005-01-15 at 21:16, Nick Piggin wrote:
> >
> >>OK I think the problem is due to swsusp allocating a very large
> >>chunk of memory before suspending. After resuming, kswapd is more
> >>or less in the same state and tries a bit too hard to free things.
> >
> >
> > I'm not sure about this theory. The normal case will be that all
> > allocations (maybe one or two order 1 or order 2 allocations if I've
> > forgotten something) are order 0 and processes are thawed after we've
> > freed all the memory we were using. Could that still trigger kswapd?
> >
>
> I've seen try to do order 8 allocations or something almost as
> ridiculous. Atomic too.

I believe you. But Bernard and I are dealing with Suspend2.

> Well, correction, I've seen _reports_. Never tried swsusp myself.

:>

> I don't think a few order 0 and 1 allocations would do any harm
> because otherwise every man and his dog would be having problems.

Yes. Suspend2 does allocate a large number of zero order allocations for
submitting I/O, but again, they're all freed prior to thawing frozen
processes.

> >
> >>Thanks for the report... I'll come up with something for you to try
> >>in the next day or so.
> >
> >
> > I'm flying to America on Monday, but I'll try to keep up with the
> > progress in this and do anything I can to help.
> >
>
> It is basically a problem with one of my patches. I should be able
> to fix it (although fixing swsusp would be nice too :) ).

:> Nevertheless, if there's something suspend2 related I should fix...

Nigel
--
Nigel Cunningham
Software Engineer, Canberra, Australia
http://www.cyclades.com

Ph: +61 (2) 6292 8028 Mob: +61 (417) 100 574