On Nov 20, 2006  16:41 -0800, Nathaniel Rutman wrote:
> >Sounds like a good start at least.  Would the addition of separate
> >operation modes like "connect only", "enqueue locks", etc be straight
> >forward?
> >  
> connect, create/destroy, c/write/read/d would be easy.  locks - locks 
> divorced from these operations?

Yes, it would be desirable from a load/test POV to create thousands of
locks on a single resource, millions of locks in total, to verify
behaviour before & after scalability changes are done for the DLM.  It
would be inconvenient to have to have thousands of clients to test this.

> >I think once you are running thousands of your clients on a single node
> >it will inevitably have problems because of task switching latency,
> >swapping, etc.  That said, if we can reasonably simulate some hundreds or
> >thousand(s) of clients per node this should give us the ability to simulate
> >any reasonable sized cluster.
>
> Which leads me to a Q: apparently the echo ioctl's expect immediate 
> results (within lock
> or obd timeouts (I should investigate)) but shouldn't real client VFS 
> ops just block?
> Say everybody is writing to 1 disk, faster than the disk can go.  I 
> would not expect errors,
> but instead slowed responses.  Pings in this case would continue to be 
> returned in a timely
> manner, so I would expect that both the client and the server would both 
> agree that nobody needs to be reconnected or evicted.

This is why we are working on adaptive timeouts.

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

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