Re: x$kghlu, Steve's shared_pool_lru_stats

  • From: Boris Dali <boris_dali@xxxxxxxx>
  • To: tanel.poder.003@xxxxxxx, oracle-l@xxxxxxxxxxxxx
  • Date: Mon, 8 Nov 2004 11:41:07 -0500 (EST)

Hi Tanel,

Thanks for the reply. Yes, the moment shared_pool_size
is set to 250MB or higher, Oracle responds by setting
_kghdsidx_count to 2 (meaning shared pool is divided
into 2 heaps/protected by 2 child latches/has 2 LRU
lists?). 

Incidently, it looks like the decision to split the
shared pool is made based on the shared_pool_size
parameter alone, not the derived value of the shared
pool, i.e. having shared_pool_size=200MB and
processes=8000, which yeilds "variable+fixed"=593MB
(much higher than say shared_pool_size=250MB,
processes=150) doesn't qualify for splitting.

I toyed around with the size of the shared pool in the
attempt to get 3 heaps, but to no avail. Even setting
shared_pool_size to 20GB didn't produce 3 heaps. Just
curious how does one get 7?

Also a more practical question (I think). If my
"optimal" shared pool size is around 250MB (i.e. at
150-200MB I get ORA-4031), would I be better off with
240MB and a single heap or at 250MB and dual heaps?

Thanks,
Boris Dali.

 --- Tanel Poder <tanel.poder.003@xxxxxxx> wrote: 
> Hi!
> If your shared pool is split to several separate
> areas protected by  separate shared pool child
> latches, then every shared pool area has  its own
> LRU lists, thus x$kghlu reports a row for each of
> them. 
> 
> Multiple shared pool areas feature is available from
> 9i - _kghdsidx_count parameter controls how many
> shared pool areas/child latches are used (max is 7).
> 
> Also, if java pool is defined, x$kghlu reports one
> additional row in 10g, maybe in 9i as well, I
> haven't checked (probably because java pool memory
> is managed by the same KGH module which handles
> shared pool).
> 
> 
> Tanel.
> 
> > Just out of curiousity, no fires - does anyone
> know
> > under what circumstanses it returns more than row
> for
> > a single instance (no RAC) database?
> > 
> > Thanks,
> > Boris Dali.
> > 
> >
>
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