Re: IOzone testing

[Jeff Layton <laytonjb-fOdFMYwuEsI@public.gmane.org>]

Jérôme Poulin wrote:
> On Sat, Sep 26, 2009 at 9:14 AM, Jeff Layton <laytonjb-fOdFMYwuEsI@public.gmane.org> wrote:
>   
>> Got it - thanks.
>>
>> At the same time, I also hit an out of space message. Why would I
>> get this message? If the checkpoints are just creating a small maker
>> then it shouldn't take much space. Unless of course, a huge number
>> of checkpoints are created.
>>
>> Thanks!
>>
>>     
> If nilfs_cleanerd is shut down, then the filesystem will fill up until
> there's no room for more data. When you delete data, only the
> nilfs_cleanerd can reclaim the space, which is why you set up a
> protection_period, deleted data will never be overwritten unless
> reclaimed by the cleanerd.
> Here is a program I made to represent the disk in a graphical form,
> you'll see the cleanerd in action:
> http://ticpu.net:8080/~jerome/lssu-gtk.py
>
> You need python-2.4+ with pygtk and nilfs-utils to run the program.
>   

Cool program - I will definitely try this.

So, let me summarize what I think I should do to test nilfs with
IOzone without the impact of the checkpoints and without filling
up the space.

- Run IOzone without cleanerd running to minimize the
impact of checkpoints on IO performance.
- Assuming I don't fill up the file system, after a run of
IOzone, I need to run cleanerd but put the protection
period to something very small (e.g. 1 second) to reclaim the
space.
- Shut down cleanerd again and run another IOzone test.
(rinse and repeat)

Does this sound about right?

Thanks!

Jeff