> On the Alpha port, you can change this at run-time using the 
> kern.mbuf.nmbclusters sysctl variable.  This is specific to only 
> a few ports (the ones that use direct-mapped pool pages). 

What's the downside of making that bigger?  I assume it's allocating 
memory.  How big is each cluster?  What's the impact of using jumbo 
packets on GBE? 


Would it be reasonable to add a boot-time switch to make it bigger 
during initialization?  I'm interested in systems that can't increase 
it on the fly?