Memory allocation performance/statistics patches

[Robert Watson]

On Sun, 17 Apr 2005, Robert Watson wrote:

> I'd like to confirm that for the first two patches, for interesting 
> workloads, performance generally improves, and that stability doesn't 
> degrade.  For the third partch, I'd like to quantify the cost of the 
> changes for interesting workloads, and likewise confirm no loss of 
> stability.

Just an FYI on some earlier testing done by a couple of people:

- Bosko Milekic has reported that the UMA changes resulted in a
   performance increase in his high bandwidth denial of service testing,
   as well as a decreased occurence of livelock.

- Scott Long has reported that the UMA changes produced a performance
   increase in MySQL testing.  However, that the combined malloc + mbuf +
   uma patches produced a slight decrease in performance.  He has not yet
   been able to try them split out to see if there's another factor at
   work, or which elements are causing the problem.

- I've observed clear micro-benchmark improvements with the UMA cache in
   place for high speed UDP packet generation in userland, as well as
   syscall tests for the allocation/free of pipes and sockets.

Robert N M Watson