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

From: Zhang, Yanmin
Date: Wed May 07 2008 - 01:06:49 EST


ïComparing 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@xxxxxxxxx>
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


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