linux-kernel - Re: [PATCH 0/8] v2 De-Couple sysfs memory directories from memory sections

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Message-ID: <4CA4AA21.9030109@austin.ibm.com>
Date:	Thu, 30 Sep 2010 10:17:53 -0500
From:	Nathan Fontenot <nfont@...tin.ibm.com>
To:	Robin Holt <holt@....com>
CC:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	linuxppc-dev@...abs.org, Greg KH <greg@...ah.com>,
	Dave Hansen <dave@...ux.vnet.ibm.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: [PATCH 0/8] v2 De-Couple sysfs memory directories from memory
 sections

On 09/29/2010 02:28 PM, Robin Holt wrote:
> On Tue, Sep 28, 2010 at 01:17:33PM -0500, Nathan Fontenot wrote:
>> On 09/28/2010 07:38 AM, Robin Holt wrote:
>>> I was tasked with looking at a slowdown in similar sized SGI machines
>>> booting x86_64.  Jack Steiner had already looked into the memory_dev_init.
>>> I was looking at link_mem_sections().
>>>
>>> I made a dramatic improvement on a 16TB machine in that function by
>>> merely caching the most recent memory section and checking to see if
>>> the next memory section happens to be the subsequent in the linked list
>>> of kobjects.
>>>
>>> That simple cache reduced the time for link_mem_sections from 1 hour 27
>>> minutes down to 46 seconds.
>>
>> Nice!
>>
>>>
>>> I would like to propose we implement something along those lines also,
>>> but I am currently swamped.  I can probably get you a patch tomorrow
>>> afternoon that applies at the end of this set.
>>
>> Should this be done as a separate patch?  This patch set concentrates on
>> updates to the memory code with the node updates only being done due to the
>> memory changes.
>>
>> I think its a good idea to do the caching and have no problem adding on to
>> this patchset if no one else has any objections.
> 
> I am sorry.  I had meant to include you on the Cc: list.  I just posted a
> set of patches (3 small patches) which implement the cache most recent bit
> I aluded to above.  Search for a subject of "Speed up link_mem_sections
> during boot" and you will find them.  I did add you to the Cc: list for
> the next time I end up sending the set.
> 
> My next task is to implement a x86_64 SGI UV specific chunk of code
> to memory_block_size_bytes().  Would you consider adding that to your
> patch set?  I expect to have that either later today or early tomorrow.
> 

No problem. I'm putting together a new patch set with updates from all of
the comments now so go ahead and send it to me when you have it ready.

-Nathan
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