Re: x$kghlu, Steve's shared_pool_lru_stats

From: Boris Dali <boris_dali_at_yahoo.ca>
Date: Mon, 8 Nov 2004 11:41:07 -0500 (EST)
Message-ID: <20041108164107.71496.qmail@web41412.mail.yahoo.com>

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_at_mail.ee> 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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Received on Mon Nov 08 2004 - 10:36:57 CST