[Haskell-cafe] Vector sort poor performance

[Alexander Pakhomov]

Hi Feilpe,

Which GHC version do you use?
With 7.6.3 I have all the same BUT Optimal'/10 260 ns. It's better than 1200 ns
but still bad. Also there are INLINEs everywhere at vector-algorithms.
Seems to be compiler problem.

21.08.2014, 18:32, "Felipe Lessa" <felipe.lessa at gmail.com>:
> On 21-08-2014 11:22, Felipe Lessa wrote:
>>  I suggest that you add a few SPECIALIZE pragmas to vector-algorithms and
>>  check its performance again.
>
> Scratch that, I remembered that one may just copy & paste :).
>
> Here's the code and criterion results:
> https://gist.github.com/meteficha/1acef6dc1e1ed81b63ae
>
> This is the relevant part:
>
> benchmarking --nothing--/10
> time 151.5 ns (151.2 ns .. 151.8 ns)
> 1.000 R² (1.000 R² .. 1.000 R²)
> mean 151.8 ns (151.6 ns .. 152.1 ns)
> std dev 868.8 ps (732.4 ps .. 1.030 ns)
>
> benchmarking --best--/10
> time 157.4 ns (157.1 ns .. 157.7 ns)
> 1.000 R² (1.000 R² .. 1.000 R²)
> mean 157.1 ns (156.6 ns .. 157.4 ns)
> std dev 1.297 ns (786.7 ps .. 2.366 ns)
>
> benchmarking Optimal/10
> time 1.173 μs (1.168 μs .. 1.180 μs)
> 1.000 R² (1.000 R² .. 1.000 R²)
> mean 1.194 μs (1.187 μs .. 1.204 μs)
> std dev 27.45 ns (22.18 ns .. 36.34 ns)
> variance introduced by outliers: 29% (moderately inflated)
>
> benchmarking Optimal'/10
> time 157.7 ns (157.5 ns .. 158.0 ns)
> 1.000 R² (1.000 R² .. 1.000 R²)
> mean 157.8 ns (157.5 ns .. 158.2 ns)
> std dev 1.178 ns (872.4 ps .. 1.965 ns)
>
> Optimal', which is a copy of Optimal, takes almost the same as --best--,
> which does no comparisons at all!
>
> So vector-algorithms really needs either to force INLINE (leading to
> code size bloat) or sprinkle SPECIALIZE pragmas everywhere.  I suggest
> contacting the package's maintainer to see what their thoughts are on
> this matter.
>
> Cheers,
>
> --
> Felipe.