Re: [Bug #14141] order 2 page allocation failures (generic)

Tobias Oetiker
2009-10-20T13:50:12Z

Hi Mel,

Today Mel Gorman wrote:

> On Tue, Oct 20, 2009 at 02:58:53PM +0200, Tobias Oetiker wrote:
> > you are saing that the problem might be even older ?
> >
> > we do have 8GB ram and 16 GB swap, so it should not fail to allocate all that
> > often
> >
> > top - 14:58:34 up 19:54, 6 users, load average: 2.09, 1.94, 1.97
> > Tasks: 451 total, 1 running, 449 sleeping, 0 stopped, 1 zombie
> > Cpu(s): 3.5%us, 15.5%sy, 2.0%ni, 72.2%id, 6.5%wa, 0.1%hi, 0.3%si, 0.0%st
> > Mem: 8198504k total, 7599132k used, 599372k free, 1212636k buffers
> > Swap: 16777208k total, 83568k used, 16693640k free, 610136k cached
> >
>
> High-order atomic allocations of the type you are trying at that frequency
> were always a very long shot. The most likely outcome is that something
> has changed that means a burst of allocations trigger an allocation failure
> where as before processes would delay long enough for the system not to notice.
>
> 1. Have MTU settings changed?

no not to my knowledge

> 2. As order-5 allocations are required to succeed, I'm surprised in a
> sense that there are only 5 failures because it implies the machine is
> actually recovering and continueing on as normal. Can you think of what
> happens in the morning that causes a burst of allocations to occur?

the burts occur all day while the machine is in use ... its just
that I was writing this at noon so only the morning had passed. So
I compared things to the day before ...

> 3. Other than the failures, have you noticed any other problems with the
> machine or does it continue along happily?

The machine seems to be fine.

> 4. Does the following patch help by any chance?

should I try this on vanilla 2.6.31.4 or ontop of your previous
patch?

we are running virtualbox 3.0.8 on this machine, virtualbox is using
the physical network interface in bridge mode access the network.
Could this have something todo with the problem ?

cheers
tobi

--
Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland
http://it.oetiker.ch tobi@oetiker.ch ++41 62 775 9902 / sb: -9900