[Linux-cluster] GFS performance test

[Steven Whitehouse]

Hi,

On Wed, 2009-12-02 at 06:58 -0800, Ray Van Dolson wrote:
> On Wed, Dec 02, 2009 at 03:53:46AM -0800, frank wrote:
> > Hi,
> > after seeing some posts related to GFS performance, we have decided to 
> > test our two-node GFS filesystem with ping_pong program.
> > We are worried about the results.
> > 
> > Running the program in only one node, without parameters, we get between 
> > 800000 locks/sec and 900000 locks/sec
> > Running the program in both nodes over the same file on the shared 
> > filesystem, the lock rate did not drop and it is the same in both nodes! 
> > What does this mean? Is there any problem with locks ?
> > 
> > Just for you info, GFS filesystem is /mnt/gfs and what I run in both 
> > nodes is:
> > 
> > ./ping_pong /mnt/gfs/tmp/test.dat 3
> > 
> > Thanks for your help.
> > 
> 
> Wow, that doesn't sound right at all (or at least not consistent with
> results I've gotten :)
> 
> Can you provide details of your setup, and perhaps your cluster.conf
> file?  Have you done any other GFS tuning?  Are we talking GFS1 or
> GFS2?
> 
> I get in the 3000-5000 locks/sec range with my GFS2 filesystem (using
> nodiratime,noatime and reducing the lock limit to 0 from 100 in my
> cluster.conf file).
> 
> The numbers you provide I'd expect to see on a local filesystem.
> 
> Ray
> 
If you are mounting with lock_nolock, then the locks are the same as for
any other local filesystem, so you'll see it works much faster than any
clustered arrangement. If the lock rate appears to be that high in the
cluster, maybe the localflocks mount parameter has been specified which
means that the locking will be done locally on each node, and is not
being done across the cluster. Ray's figures sound much more reasonable,

Steve.