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

Mel Gorman
2009-10-20T14:14:18Z

On Tue, Oct 20, 2009 at 03:50:12PM +0200, Tobias Oetiker wrote:
> 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 ...
>

Over the course of a day, how many would you see? By and large, it seems
that the problem yourself and Frans are similar except his is a lot more
severe.

> > 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?
>

Try on top of vanilla 2.6.31.4 first plase and if failures still occur,
then on top of the 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 ?
>

I do not know for sure. I'm assuming the configuration is the same on
both kernels so it's unlikely to be the issue.

--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab