Re: aim7 47% regression with 2.6.27-rc8

On Mon, 2008-10-06 at 07:38 +0200, Mike Galbraith wrote:
> On Mon, 2008-10-06 at 12:58 +0800, Zhang, Yanmin wrote:
> > Comparing with 2.6.27-rc8, aim7 result has about 47% regression with 2.6.27-rc8 on
> > my 16-core tigerton and 8 core+HyperThreading x86_64 machine.
> > 
> > I bisected it down to patch:
> > 
> > 302745699c1b675b5d2a1af87271de10e4d96b6a is first bad commit
> 
> > After I reverted the patch against 2.6.27-rc8, the regression disappears.
> > It's interesting that the regression doesn't exist on 8-core stoakley.
> 
> Looks like it's been fixed meanwhile.
I did a new quick test and the patch does fix it.

Thanks,
Yanmin

> 
> commit 07454bfff151d2465ada809bbaddf3548cc1097c
> Author: Thomas Gleixner <tglx <at> linutronix.de>
> Date:   Sat Oct 4 10:51:07 2008 +0200
> 
>     clockevents: check broadcast tick device not the clock events device
>     
>     Impact: jiffies increment too fast.
>     
>     Hugh Dickins noted that with NOHZ=n and HIGHRES=n jiffies get
>     incremented too fast. The reason is a wrong check in the broadcast