sysbench+mysql(oltp, readonly) 30% regression with 2.6.26-rc1

["Zhang, Yanmin" <yanmin_zhang@linux.intel.com>]

Comparing with kernel 2.6.25, sysbench+mysql(oltp, readonly) has many
regression with 2.6.26-rc1.

1) 8-core stoakley: 28%;
2) 16-core tigerton: 20%;
3) Itanium Montvale: 50%.

Bisect located below patch.

8f1bc385cfbab474db6c27b5af1e439614f3025c is first bad commit
commit 8f1bc385cfbab474db6c27b5af1e439614f3025c
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date:   Sat Apr 19 19:45:00 2008 +0200

    sched: fair: weight calculations
    
    In order to level the hierarchy, we need to calculate load based on the
    root view. That is, each task's load is in the same unit.



After I manually reverted the patch against 2.6.26-rc1 while fixing a couple of
conflictions/errors, sysbench oltp regression became less than 3% on 8-core
stoakley.

-yanmin