[Lustre-discuss] Is there a way to set lru_size and have it stick?

[Andreas Dilger]

On 12-Oct-09, at 12:11, Lundgren, Andrew wrote:
> I have tried using:
>
> # lctl conf_param content-MDT0000.osc.lru_size=800
>
> Seen this in the log:
> Oct 12 18:35:36 abcd0202 kernel: Lustre: Modifying parameter content- 
> MDT0000-mdc.osc.lru_size in log content-client
> Oct 12 18:35:36 abcd0202 kernel: Lustre: Skipped 1 previous similar  
> message
>
> But then on the clients, the lru_size doesn't seem to change:
>
> OSS # cat ./fs/lustre/ldlm/namespaces/*/lru_size
> 33
> 0
> 0
> 0
> 1
> 0
> 1
> 200
>
> I have also set it for the OST individually from the MDS.  It  
> doesn't seem to do anything for the other machines.
>
> Is this a permanently tunable parameter, or am I just specifying the  
> wrong setting?


My apologies.  Any parameter settable in a /proc/fs/lustre/ file can  
usually
be specified as <obd|fsname>.<obdtype>.<proc_file_name>=<value>, e.g.:

   * tunefs.lustre --param mdt.group_upcall=NONE /dev/sda1
   * lctl conf_param testfs-MDT0000.mdt.group_upcall=NONE
   * lctl conf_param testfs.llite.max_read_ahead_mb=16
   * ... testfs-MDT0000.lov.stripesize=2M
   * ... testfs-OST0000.osc.max_dirty_mb=29.15
   * ... testfs-OST0000.ost.client_cache_seconds=15
   * ... testfs.sys.timeout=40

However, it isn't currently possible to specify a conf_param tunable  
for ldlm
settings, since they do not have their own OBD device and the tunable  
code is
(unfortunately) slightly different than other parts of the Lustre proc  
tunables.

Ages and ages ago, this was done because the externally-contributed  
lprocfs code
was very buggy and we wanted to make sure that the ldlm /proc tunables  
(which
were, at the time, the only ones that were actually required for Lustre
functionality) would continue working while lprocfs was disabled until  
fixed.

Until now, there was no reason to change that code, but it makes sense  
to fix
that now...  Could you file a bug on this?

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.