From: Christoph Lameter <cl@linux-foundation.org>
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mel@csn.ul.ie>,
linux-mm@kvack.org
Subject: Re: [patch] mm: suppress pfn range output for zones without pages
Date: Thu, 11 Feb 2010 16:32:51 -0600 (CST) [thread overview]
Message-ID: <alpine.DEB.2.00.1002111626440.7201@router.home> (raw)
In-Reply-To: <alpine.DEB.2.00.1002111405120.16763@chino.kir.corp.google.com>
On Thu, 11 Feb 2010, David Rientjes wrote:
> So you want to parse this table of zone pfn ranges to determine, for
> example, whether CONFIG_HIGHMEM was enabled for i386 kernels? That
> doesn't tell you whether its CONFIG_HIGHMEM4G or CONFIG_HIGHMEM64G, so
> it's a pretty bad way to interpret the kernel config and decide whether
It tells me that there is highmem zone.
> the pfn ranges are valid or not. The only other use case would be to find
> if the values are sane when we don't have CONFIG_ZONE_DMA or
> CONFIG_ZONE_DMA32, but those typically aren't even disabled: I just sent a
> patch to the x86 maintainers to get that configuration to compile on -rc7.
CONFIG_ZONE_DMA32 is disabled on 32 bit
CONFIG_ZONE_DMA may be disabled on IA64 or other platforms that do have
priviledged areas of memory.
Strange embedded kernel configs may sometimes play tricks with ZONE_DMA.
> In other words, I don't think we need to be emitting kernel diagnostic
> messages for zones that are empty and unused just because they are enabled
> in the kernel config; no developer is going to care about parsing the
> usecase I showed in the changelog since ZONE_NORMAL is always defined.
The kernel zone based arrays will still be dimensioned based on the
configured zones even if you omit those from the display. This influences
memory allocation.
I do not feel strongly about this since I can always look at the .config
files but you are removing information from the kernel log that I have
been using in the past.
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next prev parent reply other threads:[~2010-02-11 22:33 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
2010-02-11 20:07 ` Christoph Lameter
2010-02-11 22:13 ` David Rientjes
2010-02-11 22:32 ` Christoph Lameter [this message]
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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