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From: Vlastimil Babka <vbabka@suse.cz>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Rik van Riel <riel@redhat.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Linux MM <linux-mm@kvack.org>, Mel Gorman <mgorman@suse.de>,
	Mark <markk@clara.co.uk>, Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Subject: Re: [RFC PATCH] mm: CONFIG_NR_ZONES_EXTENDED
Date: Tue, 1 Mar 2016 09:31:21 +0100	[thread overview]
Message-ID: <56D55359.3080809@suse.cz> (raw)
In-Reply-To: <CAPcyv4j1JbpuoiurRe7hbnBbxthK3wtuoQXzwQ7rAcc+2MYV9A@mail.gmail.com>

On 03/01/2016 03:06 AM, Dan Williams wrote:
> On Mon, Feb 29, 2016 at 4:06 PM, Vlastimil Babka <vbabka@suse.cz> wrote:
>> On 29.2.2016 18:55, Dan Williams wrote:
>>> On Mon, Feb 29, 2016 at 4:33 AM, Vlastimil Babka <vbabka@suse.cz> wrote:
>>>> On 02/02/2016 06:42 AM, Andrew Morton wrote:
>>>
>>> In this case it's already part of the equation because:
>>>
>>> config ZONE_DEVICE
>>>        depends on MEMORY_HOTPLUG
>>>        depends on MEMORY_HOTREMOVE
>>>
>>> ...and those in turn depend on SPARSEMEM.
>>
>> Fine, but then SPARSEMEM_VMEMMAP should be still an available subvariant of
>> SPARSEMEM with SECTION_WIDTH=0.
>
> It should be, but not for the ZONE_DEVICE case.  ZONE_DEVICE depends
> on x86_64 which means ZONE_DEVICE also implies SPARSEMEM_VMEMMAP
> since:
>
> config ARCH_SPARSEMEM_ENABLE
>         def_bool y
>         depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
>         select SPARSEMEM_STATIC if X86_32
>         select SPARSEMEM_VMEMMAP_ENABLE if X86_64
>
> Now, if a future patch wants to reclaim page flags space for other
> usages outside of ZONE_DEVICE it can do the work to handle the
> SPARSEMEM_VMEMMAP=n case.  I don't see a reason to fold that
> distinction into the current patch given the current constraints.

OK so that IUUC shows that x86_64 should be always fine without decreasing the 
range for NODES_SHIFT? That's basically my point - since there's a configuration 
where things don't fit (32bit?), the patch broadly decreases range for 
NODES_SHIFT for everyone, right?

> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
>

WARNING: multiple messages have this Message-ID (diff)
From: Vlastimil Babka <vbabka@suse.cz>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Rik van Riel <riel@redhat.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Linux MM <linux-mm@kvack.org>, Mel Gorman <mgorman@suse.de>,
	Mark <markk@clara.co.uk>, Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Subject: Re: [RFC PATCH] mm: CONFIG_NR_ZONES_EXTENDED
Date: Tue, 1 Mar 2016 09:31:21 +0100	[thread overview]
Message-ID: <56D55359.3080809@suse.cz> (raw)
In-Reply-To: <CAPcyv4j1JbpuoiurRe7hbnBbxthK3wtuoQXzwQ7rAcc+2MYV9A@mail.gmail.com>

On 03/01/2016 03:06 AM, Dan Williams wrote:
> On Mon, Feb 29, 2016 at 4:06 PM, Vlastimil Babka <vbabka@suse.cz> wrote:
>> On 29.2.2016 18:55, Dan Williams wrote:
>>> On Mon, Feb 29, 2016 at 4:33 AM, Vlastimil Babka <vbabka@suse.cz> wrote:
>>>> On 02/02/2016 06:42 AM, Andrew Morton wrote:
>>>
>>> In this case it's already part of the equation because:
>>>
>>> config ZONE_DEVICE
>>>        depends on MEMORY_HOTPLUG
>>>        depends on MEMORY_HOTREMOVE
>>>
>>> ...and those in turn depend on SPARSEMEM.
>>
>> Fine, but then SPARSEMEM_VMEMMAP should be still an available subvariant of
>> SPARSEMEM with SECTION_WIDTH=0.
>
> It should be, but not for the ZONE_DEVICE case.  ZONE_DEVICE depends
> on x86_64 which means ZONE_DEVICE also implies SPARSEMEM_VMEMMAP
> since:
>
> config ARCH_SPARSEMEM_ENABLE
>         def_bool y
>         depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
>         select SPARSEMEM_STATIC if X86_32
>         select SPARSEMEM_VMEMMAP_ENABLE if X86_64
>
> Now, if a future patch wants to reclaim page flags space for other
> usages outside of ZONE_DEVICE it can do the work to handle the
> SPARSEMEM_VMEMMAP=n case.  I don't see a reason to fold that
> distinction into the current patch given the current constraints.

OK so that IUUC shows that x86_64 should be always fine without decreasing the 
range for NODES_SHIFT? That's basically my point - since there's a configuration 
where things don't fit (32bit?), the patch broadly decreases range for 
NODES_SHIFT for everyone, right?

> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
>

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

  reply	other threads:[~2016-03-01  8:31 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-28  6:19 [RFC PATCH] mm: CONFIG_NR_ZONES_EXTENDED Dan Williams
2016-01-28  6:19 ` Dan Williams
2016-02-02  5:42 ` Andrew Morton
2016-02-02  5:42   ` Andrew Morton
2016-02-07  6:10   ` Dan Williams
2016-02-07  6:10     ` Dan Williams
2016-02-29 12:33   ` Vlastimil Babka
2016-02-29 12:33     ` Vlastimil Babka
2016-02-29 17:55     ` Dan Williams
2016-02-29 17:55       ` Dan Williams
2016-03-01  0:06       ` Vlastimil Babka
2016-03-01  0:06         ` Vlastimil Babka
2016-03-01  2:06         ` Dan Williams
2016-03-01  2:06           ` Dan Williams
2016-03-01  8:31           ` Vlastimil Babka [this message]
2016-03-01  8:31             ` Vlastimil Babka
2016-03-01 23:43             ` Dan Williams
2016-03-01 23:43               ` Dan Williams
2016-03-02  8:10               ` Vlastimil Babka
2016-03-02  8:10                 ` Vlastimil Babka

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