Thanks Andreas. I'll try a lower value for the num_threads=NNN. How low
can these values be?

- Sridharan 

> -----Original Message-----
> From: Andreas Dilger [mailto:[EMAIL PROTECTED] 
> Sent: Sunday, February 11, 2007 11:39 PM
> To: Sridharan Ramaswamy (srramasw)
> Cc: [email protected]
> Subject: Re: [Lustre-discuss] Number of processes in Lustre tunable?
> 
> On Jan 23, 2007  10:39 -0800, Sridharan Ramaswamy (srramasw) wrote:
> > I'm tring to measure the overhead of having Lustre on the 
> system.  Among
> > other things, I noticed it starts lot of processes,
> >  
> > root      4565     1  0 Jan03 ?        00:00:00 [ll_mdt_attr_14]
> > root      4636     1  0 Jan03 ?        00:00:01 [ll_ost_13]
> > root      4651     1  0 Jan03 ?        00:00:08 [ll_ost_io_13]
> > root      4550     1  0 Jan03 ?        00:00:03 [ll_mdt_14]
> > root      4516     1  0 Jan03 ?        00:00:00 [ldlm_cb_31]
> > 
> > I can account about 200 processes related to Lustre on an 
> OST node. That
> > seems a lot considering we would like to run other 
> applications on the
> > same node. Is it possible to tune these number of processes 
> down? Say
> > reduce 32 ldlm process to about 8. What kind of performance 
> degradation
> > to expect if we can do that?
> 
> You can reduce the MDS and OST process count via modprobe.conf:
> 
> option mds mds_num_threads=NNN
> option ost ost_num_threads=NNN
> 
> If this isn't good enough, you can change the count at compile time
> in lustre/include/linux/lustre-net.h
> 
> In 1.6 the number of threads will be more dynamic, depending on load.
> 
> Cheers, Andreas
> --
> Andreas Dilger
> Principal Software Engineer
> Cluster File Systems, Inc.
> 

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