Hi Szaka,

Szabolcs Szakacsits wrote:
> Hi,
>
> Good start for 2008! :-) This year seems to be quite exciting on the NTFS 
> field!
>   

So have a very good year !

> On Mon, 14 Jan 2008, Jean-Pierre ANDRE wrote:
>
>   
>> This is to announce a candidate release of an extension to ntfs-3g for file
>> ownership and protections (ntfs-3g-1.1120SC.1, based on the standard version
>> ntfs-3g-1.1120).
>>
>> Details and dowload are available on
>> http://pagesperso-orange.fr/b.andre/security.html
>>
>> The only change since the latest beta-test version (ntfs-3g-1.1120SB.5, Dec
>> 14th) is the use of an LRU cache to get the inode numbers 
>>     
>
> Cool, I'll check it out. 
>
> Btw, could you please move the /NTFS-3G directory to a hidden /.NTFS-3G? 
> I think we agreed on this sometime ago when we discussed that OS X also 
> needs to store some files in /.NTFS-3G.
>
>   
Ok, I was not aware of this request.
I will also set up a mount option to designate any location on a previously
mounted fs.

>> and the deactivation of cacheing of file attributes by FUSE. This 
>> decreases significantly the CPU usage by ntfs-3g (the impact on CPU usage 
>> by fuse is unknown) and fixes a hard link problem caused by the 
>> unawareness of hard linked files by FUSE.
>>     
>
> Hmmm, if I remember correctly then disabling FUSE attribute caching doesn't 
> solve all the problems (I'll check for the known issues). To avoid those 
> problems Miklos suggested the usage of the low-level FUSE interface and 
> this is indeed planned for a while for much better performance and less 
> code.
>   

That remains possible. The fuse test program still fails on the number
of links for a directory, but this is due to ntfs-3g not counting the
number of subdirectories.

>> I have benchmarked this version on recompiling ntfs-3g from the tarball
>> (gzip, tar, configure, make), doing about 4000 file or directory openings
>> (among which 900 were file creations). The relative CPU usage by successive 
>> versions of ntfs-3g are as follows :
>>
>> standard ntfs-3g no security           100% (reference)
>> ntfs-3g plus security no caching       130%
>> ntfs-3g plus security cached           108%
>> same plus inode number cacheing         45%
>> same without fuse attribute cacheing    47%
>>
>> An equivalent ratio is met on the number of physical reads requested by
>> ntfs-3g (242661, instead of 534743 for the reference version), but the real
>> impact on data access times is probably much less because of the cacheing
>> done by the kernel. Moreover the cacheing has no effect on writings, so there
>> should be no impact on disk throughput when copying large files.
>>     
>
> Thank you for doing this!
>
> I have also made some benchmarks. User mapping wasn't used, so I could 
> compare the speed improvements itself better with the standard version.
>
> Bonnie++ result:
>   File creation: 10% improvement
>   File stat:     50% decrease     <-- disabled fuse cache, quite probably
>   

You can just remove the FUSE timeout option to confirm your diagnosis.

>   File removal:  20% improvement
>   
> Concurrent write (tiotest):  20% improvement
>
> Unpacking kernel (23,000+ files): 50% improvement
> Running 'find' on kernel:         20% improvement
> Removing kernel tree:             40% improvement
>
> Quite good results! Moving to the low-level interface should also improve
> at least further 20-50% in general on the performance.
>   

> Btw, I think we don't need path_normalize(). FUSE should do it already. 
> Afair, paths must always start with '/' and the trailing slashes seems to 
> be always removed as well.
>   

Not so simple. "Internal" files names ($Secure, etc.) are generally 
designated
without a leading '/', and building parent directory names frequently 
leaves a
trailing '/'. So normalizing both ends appears safer (and easier) than 
finding all
occurrences of these situations.

Regards

Jean-Pierre



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