Re: Netperf TCP_RR(loopback) 10% regression in 2.6.24-rc6, comparingwith 2.6.22

[Ilpo Järvinen]

On Fri, 11 Jan 2008, Zhang, Yanmin wrote:

> On Wed, 2008-01-09 at 17:35 +0800, Zhang, Yanmin wrote: 
> > The regression is:
> > 1)stoakley with 2 qual-core processors: 11%;
> > 2)Tulsa with 4 dual-core(+hyperThread) processors:13%;
> I have new update on this issue and also cc to netdev maillist.
> Thank David Miller for pointing me the netdev maillist.
> 
> > 
> > The test command is:
> > #sudo taskset -c 7 ./netserver
> > #sudo taskset -c 0 ./netperf -t TCP_RR -l 60 -H 127.0.0.1 -i 50,3 -I 99,5 -- -r 1,1
> > 
> > As a matter of fact, 2.6.23 has about 6% regression and 2.6.24-rc's
> > regression is between 16%~11%.
> > 
> > I tried to use bisect to locate the bad patch between 2.6.22 and 2.6.23-rc1,
> > but the bisected kernel wasn't stable and went crazy.

TCP work between that is very much non-existing.

Using git-reset's to select a nearby merge point instead of default 
commit where bisection lands might be help in case the bisected kernel 
breaks.

Also, limiting bisection under a subsystem might reduce probability of 
brokeness (might at least be able to narrow it down quite a lot), e.g.

git bisect start net/


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