Re: [Gnue-dev] Cache in Common

[Stanley A. Klein]

Just a word of caution on caches.

I think we need to be careful in planning and implementing caches.  As an
application, GNUe is sitting on top of a mountain of algorithms, including
a variety of caches.  They are supposed to improve performance, but it is
also possible for caches to work at cross purposes with each other and
create performance issues.

The database systems have caches, the operating system and its device
drivers provide caches, the devices themselves provide caches, and the
processor chips have caches.  In addition, the virtual memory systems
commonly provided by operating systems are also a form of cache.  If all of
these systems work together, performance is improved, but if they work
against each other the effects on performance can be adverse.

It is much more likely to find a database system that is designed with
consideration for the caching and virtual memory strategies of the
operating system than to find an application that is designed with
consideration for the strategies of either the operating system or database
system.  

GNUe is intended to run on multiple operating systems and to use multiple
database systems.  That makes the design of a caching strategy that takes
into account either the operating system or the database system even more
difficult.


Stan Klein