Re: VM issue causing high CPU loads

[Yohan]

> > > I did only:
> > >
> > > --- linux-2.6.27.21/include/linux/sunrpc/auth.h	2009-03-23 23:04:09.000000000 +0100
> > > +++ linux-2.6.27.21/include/linux/sunrpc/auth.h	2009-05-19 16:02:35.000000000 +0200
> > > @@ -62,8 +62,12 @@ 
> > >   */
> > > - #define RPC_CREDCACHE_HASHBITS	4
> > > + #define RPC_CREDCACHE_HASHBITS	12
> > >
> > >
> > > And i test it in prod since sunday: i only have 36% of one core used by 
> > > system
> > > versus more than 3 cores used by system in another server that did a 
> > > drop_caches at morning...
> > >       
> > OK, but it's still pretty bad.  Let's tell the NFS guys.
> >
> > In http://bugzilla.kernel.org/show_bug.cgi?id=14024 we appear to have a
> > major meltdown caused by the linear search in
> > rpcauth_lookup_credcache() with Yohan's workload.
> >     
> OK. Could we please have some more details about the actual workload involved here?
>   
I add a new server CPU graph and 60s readprofile on the bugzilla

> As far as I can see, there is no RPCSEC_GSS involved, so credentials
> should never expire. They will be reused as long as processes aren't
> switching between thousands and thousands of different combinations of
> uid, gid and groups.
My servers are imap servers.
Foreach user (~15 million) it have a specific uid over ~10 nfs netapp 
storage.

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