From: Peter Zijlstra <peterz@infradead.org>
To: Alex Samad <alex@samad.com.au>
Cc: linux-kernel@vger.kernel.org, linux-mm <linux-mm@kvack.org>,
Mel Gorman <mel@skynet.ie>
Subject: Re: page swap allocation error/failure in 2.6.25
Date: Mon, 28 Jul 2008 12:04:47 +0200 [thread overview]
Message-ID: <1217239487.6331.24.camel@twins> (raw)
In-Reply-To: <20080727060701.GA7157@samad.com.au>
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.
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..
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Alex Samad <alex@samad.com.au>
Cc: linux-kernel@vger.kernel.org, linux-mm <linux-mm@kvack.org>,
Mel Gorman <mel@skynet.ie>
Subject: Re: page swap allocation error/failure in 2.6.25
Date: Mon, 28 Jul 2008 12:04:47 +0200 [thread overview]
Message-ID: <1217239487.6331.24.camel@twins> (raw)
In-Reply-To: <20080727060701.GA7157@samad.com.au>
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.
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..
--
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next prev parent reply other threads:[~2008-07-28 10:04 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-25 7:20 page swap allocation error/failure in 2.6.25 Alex Samad
2008-07-25 7:40 ` Peter Zijlstra
2008-07-27 6:07 ` Alex Samad
2008-07-28 10:04 ` Peter Zijlstra [this message]
2008-07-28 10:04 ` Peter Zijlstra
2008-07-29 0:06 ` Alex Samad
2008-07-29 9:14 ` Mel Gorman
2008-07-29 9:14 ` Mel Gorman
2008-07-29 9:58 ` Alex Samad
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