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From: Dave Hansen <dave@linux.vnet.ibm.com>
To: Nathan Fontenot <nfont@austin.ibm.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	linuxppc-dev@ozlabs.org
Subject: Re: [PATCH 1/5] v2 Split the memory_block structure
Date: Fri, 16 Jul 2010 11:33:30 -0700	[thread overview]
Message-ID: <1279305210.9207.250.camel@nimitz> (raw)
In-Reply-To: <4C40A3BC.3060504@austin.ibm.com>

On Fri, 2010-07-16 at 13:23 -0500, Nathan Fontenot wrote:
> > If the memory_block's state was inferred to be the same as each
> > memory_block_section, couldn't we just keep a start and end phys_index
> > in the memory_block, and get away from having memory_block_sections at
> > all?
> 
> Oooohhh... I like.  Looking at the code it appears this is possible.  I'll
> try this out and include it in the next version of the patch.
> 
> Do you think we need to add an additional file to each memory block directory
> to indicate the number of memory sections in the memory block that are actually
> present? 

I think it's easiest to just say that each 'memory_block' can only hold
contiguous 'memory_block_sections', and we give either the start/end or
start/length pairs.  It gets a lot more complicated if we have to deal
with lots of holes.

I can just see the hardware designers reading this thread, with their
Dr. Evil laughs trying to come up with a reason to give us a couple of
terabytes of RAM with only every-other 16MB area populated. :)  

-- Dave

WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <dave@linux.vnet.ibm.com>
To: Nathan Fontenot <nfont@austin.ibm.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linuxppc-dev@ozlabs.org,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: [PATCH 1/5] v2 Split the memory_block structure
Date: Fri, 16 Jul 2010 11:33:30 -0700	[thread overview]
Message-ID: <1279305210.9207.250.camel@nimitz> (raw)
In-Reply-To: <4C40A3BC.3060504@austin.ibm.com>

On Fri, 2010-07-16 at 13:23 -0500, Nathan Fontenot wrote:
> > If the memory_block's state was inferred to be the same as each
> > memory_block_section, couldn't we just keep a start and end phys_index
> > in the memory_block, and get away from having memory_block_sections at
> > all?
> 
> Oooohhh... I like.  Looking at the code it appears this is possible.  I'll
> try this out and include it in the next version of the patch.
> 
> Do you think we need to add an additional file to each memory block directory
> to indicate the number of memory sections in the memory block that are actually
> present? 

I think it's easiest to just say that each 'memory_block' can only hold
contiguous 'memory_block_sections', and we give either the start/end or
start/length pairs.  It gets a lot more complicated if we have to deal
with lots of holes.

I can just see the hardware designers reading this thread, with their
Dr. Evil laughs trying to come up with a reason to give us a couple of
terabytes of RAM with only every-other 16MB area populated. :)  

-- Dave


WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <dave@linux.vnet.ibm.com>
To: Nathan Fontenot <nfont@austin.ibm.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linuxppc-dev@ozlabs.org,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: [PATCH 1/5] v2 Split the memory_block structure
Date: Fri, 16 Jul 2010 11:33:30 -0700	[thread overview]
Message-ID: <1279305210.9207.250.camel@nimitz> (raw)
In-Reply-To: <4C40A3BC.3060504@austin.ibm.com>

On Fri, 2010-07-16 at 13:23 -0500, Nathan Fontenot wrote:
> > If the memory_block's state was inferred to be the same as each
> > memory_block_section, couldn't we just keep a start and end phys_index
> > in the memory_block, and get away from having memory_block_sections at
> > all?
> 
> Oooohhh... I like.  Looking at the code it appears this is possible.  I'll
> try this out and include it in the next version of the patch.
> 
> Do you think we need to add an additional file to each memory block directory
> to indicate the number of memory sections in the memory block that are actually
> present? 

I think it's easiest to just say that each 'memory_block' can only hold
contiguous 'memory_block_sections', and we give either the start/end or
start/length pairs.  It gets a lot more complicated if we have to deal
with lots of holes.

I can just see the hardware designers reading this thread, with their
Dr. Evil laughs trying to come up with a reason to give us a couple of
terabytes of RAM with only every-other 16MB area populated. :)  

-- Dave

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  reply	other threads:[~2010-07-16 18:33 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-07-15 18:30 [PATCH 0/5] v2 De-couple sysfs memory directories from memory section size Nathan Fontenot
2010-07-15 18:30 ` Nathan Fontenot
2010-07-15 18:37 ` [PATCH 1/5] v2 Split the memory_block structure Nathan Fontenot
2010-07-15 18:37   ` Nathan Fontenot
2010-07-16  0:06   ` KAMEZAWA Hiroyuki
2010-07-16  0:06     ` KAMEZAWA Hiroyuki
2010-07-16  0:06     ` KAMEZAWA Hiroyuki
2010-07-16 15:29     ` Nathan Fontenot
2010-07-16 15:29       ` Nathan Fontenot
2010-07-16 15:29       ` Nathan Fontenot
2010-07-16 17:15   ` Dave Hansen
2010-07-16 17:15     ` Dave Hansen
2010-07-16 17:15     ` Dave Hansen
2010-07-16 18:23     ` Nathan Fontenot
2010-07-16 18:23       ` Nathan Fontenot
2010-07-16 18:23       ` Nathan Fontenot
2010-07-16 18:33       ` Dave Hansen [this message]
2010-07-16 18:33         ` Dave Hansen
2010-07-16 18:33         ` Dave Hansen
2010-07-16 18:45       ` Dave Hansen
2010-07-16 18:45         ` Dave Hansen
2010-07-16 18:45         ` Dave Hansen
2010-07-15 18:38 ` [PATCH 2/5] v2 Create new 'end_phys_index' file Nathan Fontenot
2010-07-15 18:38   ` Nathan Fontenot
2010-07-16  0:08   ` KAMEZAWA Hiroyuki
2010-07-16  0:08     ` KAMEZAWA Hiroyuki
2010-07-16  0:08     ` KAMEZAWA Hiroyuki
2010-07-16 15:36     ` Nathan Fontenot
2010-07-16 15:36       ` Nathan Fontenot
2010-07-16 15:36       ` Nathan Fontenot
2010-07-15 18:39 ` [PATCH 3/5] v2 Change the mutex name in the memory_block struct Nathan Fontenot
2010-07-15 18:39   ` Nathan Fontenot
2010-07-16 17:16   ` Dave Hansen
2010-07-16 17:16     ` Dave Hansen
2010-07-16 17:16     ` Dave Hansen
2010-07-15 18:40 ` [PATCH 4/5] v2 Update sysfs node routines for new sysfs memory directories Nathan Fontenot
2010-07-15 18:40   ` Nathan Fontenot
2010-07-16  0:12   ` KAMEZAWA Hiroyuki
2010-07-16  0:12     ` KAMEZAWA Hiroyuki
2010-07-16  0:12     ` KAMEZAWA Hiroyuki
2010-07-16 15:40     ` Nathan Fontenot
2010-07-16 15:40       ` Nathan Fontenot
2010-07-16 15:40       ` Nathan Fontenot
2010-07-15 18:41 ` [PATCH 5/5] v2 Enable multiple sections per directory for ppc Nathan Fontenot
2010-07-15 18:41   ` Nathan Fontenot
2010-07-16 17:18   ` Dave Hansen
2010-07-16 17:18     ` Dave Hansen
2010-07-16 17:18     ` Dave Hansen

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