Re: cyclic test results on 8 way (2.6.23.1-rt7 through 2.6.23.1-rt11)

[Darren Hart <dvhltc@us.ibm.com>]

On Tuesday 13 November 2007 06:15:03 Steven Rostedt wrote:
> On Tue, 13 Nov 2007, Jaswinder Singh wrote:
> > On Nov 8, 2007 1:04 PM, Darren Hart <dvhltc@us.ibm.com> wrote:
> > > # ./cyclictest -n -i 10000 -l 10000 -p 95
> >
> > 10000 (10 milliseconds) interval seems to be quite big for current
> > machine. 10 milliseconds is good for 10 to 15 years old machine but
> > not for latest machines.
> >
> > I think we should try -i 1000 or -i 4000 .
>
> heh, I test with -i 250.

Someone, I'm sorry I can't recall who atm, suggested that using a larger 
interval would allow for more variance to be introduced - not keeping the 
caches so hot for this particular test by not spending so much time on the 
cpu.  Is this a valid approach?  Perhaps running multiple runs with both very 
tight intervals (like Steve's case) and some longer intervals to ensure we 
can handle both cases - since both are common in practice.

Thanks,

-- 
Darren Hart
IBM Linux Technology Center
Realtime Linux Team