linux-ext4 - Re: [PATCH v3 0/2] ext4: increase mbcache scalability

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Date:	Sat, 19 Oct 2013 18:06:27 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	Thavatchai Makphaibulchoke <thavatchai.makpahibulchoke@...com>
CC:	Andreas Dilger <adilger@...ger.ca>,
	"Theodore Ts'o" <tytso@....edu>,
	"linux-ext4@...r.kernel.org List" <linux-ext4@...r.kernel.org>,
	"Chandramouleeswaran, Aswin" <aswin@...com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH v3 0/2] ext4: increase mbcache scalability

On 10/18/13 7:43 AM, Thavatchai Makphaibulchoke wrote:
> On 10/03/2013 09:22 PM, Andreas Dilger wrote:
> 
>>
>> This is a pretty significant price to pay for SELinux in any case.
>> I guess it is probably lower overhead with 256-byte inodes, but
>> anything that adds 5-25% overhead shouldn't be taken for granted.
>>
>> Cheers, Andreas
>>
> 
> So far we have determined that,
> 
> - With SELinux enabled a ramdisk filesytem, with default node size of 128 bytes, extended xattr is generated
> - In one of the aim7 workload, mbcache has a hit ratio of about 65%
> 
> Seems like mbcache itself and the mbcache lock optimization attempt
> by the patch could actually improve performance for a real word
> system where extended xattr is employed. I believe the patch should
> go in if there isn't any concern.

But the 128-byte inode size is not common, so in general, mbcache isn't
exercised that often.

(still, it is there, and if there's a nice scalability patch for it,
it's probably worth it).

-Eric

> Please let me know if there is any comment or concern about the patch.
> 
> Thanks,
> Mak.
> 
> 
> 

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