[Ocfs2-tools-devel] [PATCH 15/15] dx_dirs v10: enable metaecc and indexed-dirs support as default features

[Coly Li]

On 04/01/2010 06:58 AM, Mark Fasheh Wrote:
> On Thu, Mar 25, 2010 at 03:52:22AM +0800, Coly Li wrote:
>> metaecc feature enables ECC checking for meta data, which helps the file
>> system consistency. indexed-dirs feature enables indexed tree for
>> directories, which improves lookup performance for large scale
>> directories.
>>
>> This patch enables metaecc and indexed-dirs support as default features.
> 
> Nice patch, but not yet :)  We should let the dx_dir patches get some testing
> in ocfs2-tools.git first - Sunil in particular had mentioned that to me earlier.
> 

Do you mean this patch should only enable indexed-dirs so far ?
> 
> Regarding metaecc, I'm not sure if we ever intended that to be enabled by
> default as it uses more cpu when enabled. That said, cpus are so fast these
> days...

Thanks for your review.

IMHO, metaecc only check ecc for meta data, in common cases (reasonable big files), the CPU cost should be reasonable
acceptable. I did some basic test (xen domU on an 8 cores machine), like create/delete big file, create/delete small
files, a quite rough performance
number looks like this,
                           metaecc     no mataecc   metaecc cost
create 1GB file           0m17.837s    0m18.159s    -1.7%
create 10K empty files    0m40.595s    0m38.730s    +4.8%
delete 10K empty files     0m9.463s     0m9.055s    +4.3%

Considering we get ecc checking for meta data, the performance penalty is reasonable.

Therefore, I still suggest to consider enabling metaecc as default feature.

-- 
Coly Li
SuSE Labs