linux-kernel - Re: [PATCH][BUGFIX][RFC] fix soft lock up at NFS mount by making limitation of dentry

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Message-ID: <47DA09F0.2030506@np.css.fujitsu.com>
Date:	Fri, 14 Mar 2008 14:15:28 +0900
From:	Kentaro Makita <k-makita@...css.fujitsu.com>
To:	linux-kernel@...r.kernel.org
Cc:	dgc@....com
Subject: Re: [PATCH][BUGFIX][RFC] fix soft lock up at NFS mount by making
 limitation of dentry_unused

Hi David
On Thu, 6 Mar 2008 16:54:16 +1100  David Chinner wrote:
>> No, we need a smarter free list structure. There have been several attempts
>> at this in the past. Two that I can recall off the top of my head:
>>
>> 	- per node unused LRUs
>> 	- per superblock unusued LRUs
>> I guess we need to revisit this again, because limiting the size of
>> the cache like this is not an option.
I 'm interesting in your patch. I 'll test two patches above if there
is newer version based on latest kernel.

>> Try something that relies on leaving the working set on the unused
>> list, like NFS server benchmarks that have a working set of tens of
>> million of files....
>>
I tested following, and I found no regressions except one case.
 - kernbench-0.24 on local ext3 and nfs
 - dbench-3.04 on local ext3 and nfs
 - IOzone-3.291 on local ext3 and nfs
-Basic file operations (create/delete/list/copy/move) on local ext3 and nfs

but I found one performance regression in my patch at following case.
 - On local ext3, remove 1,000,000 files in a directory spends 23% more time.
 (18m34.901s to 21m55.047s)

I 'm trying to fix it and post again.
Thank you for your suggestion.

Best Regards,
Kentaro Makita

View attachment "regression test results" of type "text/plain" (5477 bytes)