Re: swappiness=0 makes software suspend fail.

[Rob Landley <rob@landley.net>]

On Sunday 30 May 2004 18:23, Oliver Neukum wrote:
> Am Sonntag, 30. Mai 2004 21:47 schrieb Pavel Machek:
> > > Until something like this goes through, please don't fuglify
> > > vmscan.c any more than it is... do the saving and restoring
> > > thing that Nigel suggested please.
>
> Isn't that a race condition with setting swapiness?

During suspend?  Not really.  If it's done from the userspace script, it's 
done before the suspend is triggered, and undone after suspend comes back.  
No problem there.  If it's done in the kernel, then all the userspace 
thingies that might play with it have already been frozen, it's never touched 
from interrupt context...  What would you be locking _against_?

Swappiness isn't really twiddled from a lot of places.  Maybe your init script 
touches it.  Other than that, you have to be root, and you pretty much have 
to do it manually.  Touching this tuning knob is about as common as touching 
/proc/sys/net/ipv4/tcp_ecn or /proc/sys/kernel/panic.

The failure condition is graceful, by the way.  The suspend doesn't free 
enough memory, and thus resumes userspace immediately.  Kind of annoying if 
you've packed away your laptop to let it power down (since it can take a good 
45 seconds to do so, depending on how fragmented your swap file and memory 
and such are...)

> 	Regards
> 		Oliver

Rob

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