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Intel Fortran now 20% faster than C, fastest language on Shootout

shootout.alioth.debian.org

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Re: Intel Fortran now 20% faster than C, fastest language on Shootout

#41

Post by igouy »

chalst wrote: post #36
gcp wrote: post #30

Earlier quoted context omitted.

This study says close to nothing about "Fortran" and "C", or about any of the other languages involved. Sorry, but I disagree here. It's one of the best resources out there for getting numbers on the relative performance of languages, despite the pitfalls. The implementations of popular languages are well tuned (sometimes extremely so), the used compilers and settings are quite sane, and the benchmark programs are fa…

Median is a bad choice, because it completely ignores just how bad the worst performance holes are for a compiler. Discarding outliers is bad methodology in this case.

The outliers are not discarded. The outliers are shown both in the chart and in the table (Fortran Intel 25.26).

http://shootout.alioth.debian.org/u64q/which-programming-lan...

Re: Intel Fortran now 20% faster than C, fastest language on Shootout

#42

Post by igouy »

dalke wrote: post #12
chj wrote: post #7

These reports are worse than useless. Any person with good understanding of computing knows that implementation plays a huge part in it. Why people wasting their time comparing speed of different programming languages while they should focus on different implementations. I guess the latter one is difficult so people all try to avoid it, and the first one is just so easy to do and everybody is doing it.

Which of course the web site freely acknowledges. At the bottom of that page states the real question is "Which of these programming language implementations have the fastest benchmark programs?"

And at the top of that page ;-)

Re: Intel Fortran now 20% faster than C, fastest language on Shootout

#43

Post by xixi77 »

stephencanon wrote: post #37
gcp wrote: post #30

Earlier quoted context omitted.

This study says close to nothing about "Fortran" and "C", or about any of the other languages involved. Sorry, but I disagree here. It's one of the best resources out there for getting numbers on the relative performance of languages, despite the pitfalls. The implementations of popular languages are well tuned (sometimes extremely so), the used compilers and settings are quite sane, and the benchmark programs are fa…

The median really is a spectacularly bad choice when there are so few data points, and especially when thinking about performance. If A and B get 3x faster, but C gets 3x slower, then your overall workload gets slower, even though the "median performance improvement" is 3x. Obviously the effect is magnified with only 3 data points, but the number of points used in the examples on that page is not so much greater as t…

Mean would be a better choice if a typical real-world application were split approximately equally between each of these tasks. Which is of course patently untrue, particularly so because writing number-crunching code in Fortran does not prevent you from writing your hash-table code in something else (note how the best C binary-trees code is actually calling an external library).

Comparison of medians is nice because it shows that for approximately half of fairly diverse tasks one language is faster than another, which imo is a much more interesting statistic.

Re: Intel Fortran now 20% faster than C, fastest language on Shootout

#45

Post by chalst »

igouy wrote: post #41
chalst wrote: post #36

Earlier quoted context omitted.

Median is a bad choice, because it completely ignores just how bad the worst performance holes are for a compiler. Discarding outliers is bad methodology in this case.

The outliers are not discarded. The outliers are shown both in the chart and in the table (Fortran Intel 25.26). http://shootout.alioth.debian.org/u64q/which-programming-lan...

Median can be described as what you get when you discard all but the centremost value or two as outliers.

Re: Intel Fortran now 20% faster than C, fastest language on Shootout

#46

Post by gcp »

chalst wrote: post #45
igouy wrote: post #41

Earlier quoted context omitted.

The outliers are not discarded. The outliers are shown both in the chart and in the table (Fortran Intel 25.26). http://shootout.alioth.debian.org/u64q/which-programming-lan...

Median can be described as what you get when you discard all but the centremost value or two as outliers.

True, but what is centremost still depends on the data you just threw away. So this is pretty lame and meaningless.

Re: Intel Fortran now 20% faster than C, fastest language on Shootout

#48

Post by igouy »

chalst wrote: post #45
igouy wrote: post #41

Earlier quoted context omitted.

The outliers are not discarded. The outliers are shown both in the chart and in the table (Fortran Intel 25.26). http://shootout.alioth.debian.org/u64q/which-programming-lan...

Median can be described as what you get when you discard all but the centremost value or two as outliers.

You don't seem to have even looked at the web page.

For each programming language implementation, that web page shows 7 descriptive values - not just the median!

As I've already said - The outliers are not discarded. The outliers are shown both in the chart and in the table.

Re: Intel Fortran now 20% faster than C, fastest language on Shootout

#49

Post by chalst »

gcp wrote: post #46
chalst wrote: post #45

Earlier quoted context omitted.

Median can be described as what you get when you discard all but the centremost value or two as outliers.

True, but what is centremost still depends on the data you just threw away. So this is pretty lame and meaningless.

What the outliers are is always distribution dependent.

Re: Intel Fortran now 20% faster than C, fastest language on Shootout

#50

Post by chalst »

igouy wrote: post #48
chalst wrote: post #45

Earlier quoted context omitted.

Median can be described as what you get when you discard all but the centremost value or two as outliers.

You don't seem to have even looked at the web page. For each programming language implementation, that web page shows 7 descriptive values - not just the median! As I've already said - The outliers are not discarded. The outliers are shown both in the chart and in the table.

"7 descriptive values" - Indeed that is true. But the median is used for the ranking and that is why I criticise it.

The worst value for Fortran, one of the included values, is more than five times worse than that for C. This suggests (not proves) that the Intel Fortran compiler has worse performance holes than gcc C that show up for some, but not all, of these benchmarks.

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