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

[Mike Galbraith <efault@gmx.de>]

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On Thu, 2008-05-08 at 14:35 +0800, Zhang, Yanmin wrote: 
> On Wed, 2008-05-07 at 18:26 +0200, Peter Zijlstra wrote: 
> > On Wed, 2008-05-07 at 12:55 +0800, Zhang, Yanmin wrote:
> > > 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.
> > 
> > Does this patch help?
> With the patch, oltp testing result is about 50% worse than the one of pure
> 2.6.26-rc1.

Hm.  I was doing some sysbench+postgress(oltp, ro) testing on my little
Q6600 box this morning, and saw a different picture.

In attached pdf, .bkl refers to Linus' BKL patch, .weight is the weight
fix, both are applied to git.today.  The script I used is also attached.

	-Mike  

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