* Madhavan Srinivasan <maddy@xxxxxxxxxxxxxxxxxx> wrote:
> Performance data for different FAULT_AROUND_ORDER values from 4 socket
> Power7 system (128 Threads and 128GB memory) is below. perf stat with
> repeat of 5 is used to get the stddev values. This patch create
> FAULT_AROUND_ORDER Kconfig parameter and defaults it to 3 based on the
> performance data.
>
> FAULT_AROUND_ORDER Baseline 1 3 4 5 7
>
> Linux build (make -j64)
> minor-faults 7184385 5874015 4567289 4318518 4193815 4159193
> times in seconds 61.433776136 60.865935292 59.245368038 60.630675011 60.56587624 59.828271924
> stddev for time ( +- 1.18% ) ( +- 1.78% ) ( +- 0.44% ) ( +- 2.03% ) ( +- 1.66% ) ( +- 1.45% )
Ok, this is better, but it is still rather incomplete statistically,
please also calculate the percentage difference to baseline, so that
the stddev becomes meaningful and can be compared to something!
As an example I did this for the first line of measurements (all
errors in the numbers are mine, this was done manually), and it gives:
> stddev for time ( +- 1.18% ) ( +- 1.78% ) ( +- 0.44% ) ( +- 2.03% ) ( +- 1.66% ) ( +- 1.45% )
+0.9% +3.5% +1.3% +1.4% +2.6%
This shows that there is probably a statistically significant
(positiv) effect from the change, but from these numbers alone I would
not draw any quantitative (sizing, tuning) conclusions, because in 3
out of 5 cases the stddev was larger than the effect, so the resulting
percentages are not comparable.
Please do this calculation for all the other lines as well and also
close all the numbers with a conclusion section where you *analyze*
the results, outline the statistics and compare the various workloads
and how the tuning affects them and don't force the readers of the
commit guess what it all means and how significant it all is!
Thanks,
Ingo
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