changing max_connections in postgresql on FreeBSD 5.4

[Bruce Walker]

Sean Chittenden wrote:

>>Will more RAM become available to postgresql if I change the
>>kernel-values mentioned above to half the size?
>>    
>>
>
>Yes, it will raise the in-kernel limits so that PostgreSQL can
>allocate more RAM for its user-land cache.
>
>You will probably have a better ROI in terms of performance by
>increasing the kernel's caching parameters as opposed to PostgreSQL's
>cache.  You need both, don't get me wrong, but there is lots of
>performance to be gained by increasing the amount of caching the
>kernel does.  -sc
>  
>

Any generally good rules of thumb you could share?  Which kernel caching 
are you referring to (ie disk, ...) ?

Thanks!