RE: 2.1.17 performance issues

[xoror@infuse.org]

On Wed, 16 Apr 2003, Howard Chu wrote:
> 
> All else being equal, any uniprocessor machine is always faster than a
> multiprocessor machine. That is, one PIII/1000 will be faster than two
> PIII/500s, comparing apples to apples. In your case, it's definitely not
> surprising that the PIII/1000 is faster than a pair of 400MHz SPARCs.
> 
> Since you say that the performance degradation persists past a directory
> restart, it sounds like your BDB environment has run out of resources. You
> should examine the statistics that db_stat provides. You should read the
> SleepyCat documentation on how to use the Berkeley DB library.

I have gone through the cache settings again and now have solved my 
problem. The DB_CONFIG needs to be set before you create anything.
A cache file on disk will be created. This explains why a restart of slapd 
doesn't help a thing.

I've now set the cachesize to 300MB and reimported all the data, The 
performance is now good. (still ldbm is twice as fast as back-bdb.) i've 
done more then 50k operations and i'm pretty confident that the cause was 
the cachesize.

I still have a question left. Why is the cache maintained on disk? Why is 
swapping out old pages/entries and swapping in new pages/entries so slow?
Does this imply when you have a large cachefile swapping out/in takes a 
lot longer then a small cache file ?