Re: [Xen-users] Re: Memory resizing

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> So the kernel still has 7800MB of memory, (7800-160)MBs eaten up by balloon
> driver and 160MBs available to userspace, right? In that case, it seems
> it's rather an issue of VM subsystem in Linux.

Well, the kernel is probably thinking "Arrrg I've almost used all physical 
memory!  Must free some now in case I run out!".  Seems odd that it'd do that 
rather than swapping - but how much free physical memory did you have?  Is it 
possible that with other tasks running too you'd run out (or quite low) of 
physical memory?

The OOM killer is presumably worried that the kernel will run out of ram and 
not be able to use it for essential kernel data structures...

The easy fix for you is probably to either remove the OOM killer (I think it's 
a compile-time option, and some people would like to see it removed 
completely) or to creat the domain smaller to start with.

> I wonder if playing with altering kernel's swappiness would help in that...
> I tried to make 8GB swap but that didn't help much.

Hmmmm.  Not sure, but I'd be more comfortable with reducing the "incentive" to 
the OOM killer in terms of physical memory set up, rather than trying to just 
increase swap and hope...

Good luck!

Btw, this behaviour could be thought of  as a bug (in that we're making Linux 
do silly things) so it'd be worth posting a bug on BugZilla and sending 
details to the xen-devel list - if you have time, that is.

Cheers,
Mark

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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