Re: [RFC] [patch 0/3] i_version update for ext4

[Cordenner jean noel <jean-noel.cordenner@bull.net>]

Andreas Dilger a écrit :
> On Jan 23, 2007  18:23 +0100, Cordenner jean noel wrote:
>> I've updated what was previously the change attribute patch for ext4 
>> initially posted by Alexandre Ratchov. The previous patch was 
>> introducing a change_attribute field, now it uses the i_version field of 
>> the inode.
>>
>> The i_version field is a counter that is set on every inode creation and 
>> that is incremented every time the inode data is modified (similarly to 
>> the "ctime" time-stamp).
>> The aim is to fulfill NFSv4 requirements for rfc3530.
>> For the moent, the counter is only a 32bit value but it is planned to be 
>> 64bit as required.
>>
>> The patch is divided into 3 parts, the vfs layer, the ext4 specific code 
>> and an user part to check i_version changes via stat.
> 
> Have you had a chance to look at the performance impact of this change
> (possible with oprofile)?  Always marking the inodes dirty for ext3
> may have some noticable overhead.
>

I did some tests using fileop with the previous version of the patch 
which was very similar. I was surprised that there was no noticable 
overhead:
  http://www.bullopensource.org/ext4/change_attribute/index.html

I will use oprofile to check it again.