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From: Andrew Morton <akpm@linux-foundation.org>
To: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>,
	linux-mm@kvack.org, Christoph Lameter <cl@linux-foundation.org>
Subject: Re: [patch] mm: suppress pfn range output for zones without pages
Date: Thu, 11 Feb 2010 14:27:34 -0800	[thread overview]
Message-ID: <20100211142734.24df7447.akpm@linux-foundation.org> (raw)
In-Reply-To: <alpine.DEB.2.00.1002111324280.5705@chino.kir.corp.google.com>

On Thu, 11 Feb 2010 13:26:37 -0800 (PST)
David Rientjes <rientjes@google.com> wrote:

> On Thu, 11 Feb 2010, Mel Gorman wrote:
> 
> > > free_area_init_nodes() emits pfn ranges for all zones on the system.
> > > There may be no pages on a higher zone, however, due to memory
> > > limitations or the use of the mem= kernel parameter.  For example:
> > > 
> > > Zone PFN ranges:
> > >   DMA      0x00000001 -> 0x00001000
> > >   DMA32    0x00001000 -> 0x00100000
> > >   Normal   0x00100000 -> 0x00100000
> > > 
> > > The implementation copies the previous zone's highest pfn, if any, as the
> > > next zone's lowest pfn.  If its highest pfn is then greater than the
> > > amount of addressable memory, the upper memory limit is used instead.
> > > Thus, both the lowest and highest possible pfn for higher zones without
> > > memory may be the same.
> > > 
> > > The output is now suppressed for zones that do not have a valid pfn
> > > range.
> > > 
> > 
> > I see no problem with the patch. Was it a major problem or just
> > confusing?
> > 
> 
> It was just confusing, I don't think anybody would be parsing the kernel 
> log for this specifically to determine whether ZONE_NORMAL exists :)
> 
> > > Cc: Mel Gorman <mel@csn.ul.ie>
> > > Signed-off-by: David Rientjes <rientjes@google.com>
> > 
> > Reviewed-by: Mel Gorman <mel@csn.ul.ie>
> > 
> 
> Thanks!

I ducked this patch because Christoph's complaint sounded reasonable -
by suppressing this output we're removing information.

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  reply	other threads:[~2010-02-11 22:28 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-02-11  9:29 [patch] mm: suppress pfn range output for zones without pages David Rientjes
2010-02-11 12:25 ` Mel Gorman
2010-02-11 21:26   ` David Rientjes
2010-02-11 22:27     ` Andrew Morton [this message]
2010-02-11 20:07 ` Christoph Lameter
2010-02-11 22:13   ` David Rientjes
2010-02-11 22:32     ` Christoph Lameter
2010-02-11 23:02       ` [patch v2] " David Rientjes
2010-02-12 15:44         ` Christoph Lameter
2010-02-11 22:33     ` [patch] " Andrew Morton

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