Re: db_block_lru_latches

Hi Daud,

The key to the number of db_block_lru_latches is to have at least enough (govern by the number of buffer pools you have) and enough to reduce contention to a minimum (govern by the sleeps to gets for cache buffers lru chain statistic in vs.$latch or as documented in statspack).

Having more than necessary means a bit more overhead inspecting all the lru chains (and grabbing the necessary latches) when DBWRs especially need to compile their write batches and the such. This is unnecessary overhead if just the maximum is assigned (which I think BTW has increased since the formula you provided).

I would recommend keeping tabs on the contention for these latches and assign as many as necessary.

Cheers

Richard

"Daud" <daud11_at_hotmail.com> wrote in message news:f0bf3cc3.0207300540.3e88d45_at_posting.google.com...
> From oracle documentation, it says that using the default value (1??)
> for db_block_lru_latches may not be good enough especially when # of
> db writers is set to more than 1. My question is will it be ok to just
> set it to the maximum which is # of cpu x 2 x 3? Any impact on the
> performance setting it to the max? The value of db_block_buffers is
> 100,000.
>
> rgds
> Daud
Received on Tue Jul 30 2002 - 09:24:20 CDT