linux-kernel - Re: [PATCH 0/4] De-couple sysfs memory directories from memory sections

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Date:	Thu, 20 Jan 2011 10:51:44 -0600
From:	Nathan Fontenot <nfont@...tin.ibm.com>
To:	Greg KH <greg@...ah.com>
CC:	linux-mm@...ck.org, linuxppc-dev@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Robin Holt <holt@....com>
Subject: Re: [PATCH 0/4] De-couple sysfs memory directories from memory sections

On 01/20/2011 10:45 AM, Greg KH wrote:
> On Thu, Jan 20, 2011 at 10:36:40AM -0600, Nathan Fontenot wrote:
>> The root of this issue is in sysfs directory creation. Every time
>> a directory is created a string compare is done against sibling
>> directories ( see sysfs_find_dirent() ) to ensure we do not create 
>> duplicates.  The list of directory nodes in sysfs is kept as an
>> unsorted list which results in this being an exponentially longer
>> operation as the number of directories are created.
> 
> Again, are you sure about this?  I thought we resolved this issue in the
> past, but you were going to check it.  Did you?
> 

Yes, the string compare is still present in the sysfs code.  There was
discussion around this sometime last year when I sent a patch out that
stored the directory entries in something other than a linked list.
That patch was rejected but it was agreed that something should be done.

-Nathan
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