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Re: [Linux-cluster] gfs2_tool settune demote_secs


On Mon, 2009-10-12 at 13:07 +0300, Kaloyan Kovachev wrote:
> Hi,
> On Fri, 09 Oct 2009 18:01:36 +0100, Steven Whitehouse wrote
> > Hi,
> > 
> > The idea is that is should be self-tuning now, adjusting itself to the
> > conditions prevailing at the time. If there are any remaining
> > performance issues though, we'd like to know so that they can be
> > addressed,
> > 
> I have noticed a possible performance issue while experimenting with
> ping_pong, but the test is representing normal operation.
The ping_pong test uses fcntl() locks. These go through dlm_controld and
are independent of the filesystem, whether you are using GFS/GFS2 (or
maybe even OCFS2 now as well). So these are not the same as the glocks
that the last message was referring to.

> The setup:
>  3 node cluster (Node1, Node2 and Node3) with shared GFS2 partition
>  1. Starting ping_pong on one of the nodes (Node1) i get several thousands
> (30k+) of locks per second
>  2. Stopping it after a while and immediately starting (moving) it to Node2
> (just like a shared service resource after failover) the number of locks goes
> below 2000
>  Probably because the locks are held on Node1, but then even after hours it
> does not go back to 30k+ locks per second and stays at <2000
>  3. Stopping ping_pong on Node2 and starting it again on the same or another
> node (Node1 or Node3) after 10-20min there are again 30k+ locks per second
>  Not sure if demote_secs would help, because i can't test, but it would be
> great to have the locks released from Node1 to Node2 after some time at step
> 2. not 3.
What options have you got in your cluster.conf relating to plocks? What
kernel are you using? 


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