Scalability of 2.12

[Samuel J. Greear]

I ran sysbench on a recent master against both PostgreSQL and MySQL to
see where we were at scalability-wise and the resulting graph can be
seen here:

http://www.flickr.com/photos/87116893@N00/6215939623/sizes/o/in/photostream/

This shows, while not excellent, fairly good use of all four cores in
my test system and this definitely marks a real milestone for us as a
project. Although we have a ways to go in this department we are in
astoundingly better shape than we were even a few short releases ago,
when this graph would have been nearly flat. ( See
http://people.freebsd.org/~kris/scaling/dfly.html -- note that these
results absolutely cannot be directly compared )

Years of preparatory work enabled this performance boon in relatively
short order and without any major stability issues. Thanks to all for
their hard work (coding, testing or otherwise), let's keep it up.

Sam