Re: page swap allocation error/failure in 2.6.25

Alex Samad
2008-07-29T00:06:18Z

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On Mon, Jul 28, 2008 at 12:04:47PM +0200, Peter Zijlstra wrote:
> On Sun, 2008-07-27 at 16:07 +1000, Alex Samad wrote:
> > On Fri, Jul 25, 2008 at 09:40:01AM +0200, Peter Zijlstra wrote:
> > > On Fri, 2008-07-25 at 17:20 +1000, Alex Samad wrote:
> > > > Hi
> >
> > [snip]
> >
> > >
> > >
> > > Its harmless if it happens sporadically.
> > >
> > > Atomic order 2 allocations are just bound to go wrong under pressure.
> > can you point me to any doco that explains this ?
>
> An order 2 allocation means allocating 1<<2 or 4 physically contiguous
> pages. Atomic allocation means not being able to sleep.
>
> Now if the free page lists don't have any order 2 pages available due to
> fragmentation there is currently nothing we can do about it.

Strange cause I don't normal have a high swap usage, I have 2G ram and
2G swap space. There is not that much memory being used squid, apache is
about it.

>
> I've been meaning to try and play with 'atomic' page migration to try
> and assemble a higher order page on demand with something like memory
> compaction.
>
> But its never managed to get high enough on the todo list..
>
>

--
"I looked the man in the eye. I found him to be very straightforward and trustworthy... I was able to get a sense of his soul."

- George W. Bush
06/16/2001
after meeting Russian President Vladimir Putin

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