[ltp] Aggressive Powersaving

[Micha]

On 10/02/2010 13:01, Tino Keitel wrote:
> On Tue, Feb 09, 2010 at 22:20:36 +0000, Pedro Ribeiro wrote:
>
> [...]
>
>> Can you get it to work properly with XFS on .32 or .33? I can't spin
>> down my hard drive for more than 20 seconds... even with laptop mode.
>
> I use ext3 and ext4, but I saw some XFS related stuff in the
> laptop_mode helper script:
>
>      # (2.6.7 upwards)
>      # And not for these either. These are in centisecs,
>      # not USER_HZ, so we have to use $AGE, not $XFS_AGE.
>      echo $AGE>  /proc/sys/fs/xfs/age_buffer_centisecs
>      echo $AGE>  /proc/sys/fs/xfs/xfssyncd_centisecs
>      echo 3000>  /proc/sys/fs/xfs/xfsbufd_centisecs
>
> Regards,
> Tino

I have to admit that I don't remember much although I was involved in the work 
to make this work (I was using xfs at the time, ext4 right now). Some nobs were 
added to play with the xfs journal update time.

Take a look at the documentation or the demo laptop mode start script, it should 
have an example of how to control xfs to change the journal update time.

The problem is that the journal mechanism bypasses the disk buffer that is 
controlled by noflushd and writes directly to disk so you need to change it's 
update time