On Sun, Jul 29, 2012 at 6:43 PM, Dmitry Olshansky <dmitry.olsh@gmail.com> wrote:

On 29-Jul-12 18:17, Andrei Alexandrescu wrote:

On 7/29/12 8:17 AM, Gor Gyolchanyan wrote:

std.variant is so incredibly slow! It's practically unusable for
anything, which requires even a tiny bit of performance.

You do realize you actually benchmark against a function that does
nothing, right? Clearly there are ways in which we can improve
std.variant to the point initialization costs assignment of two words,
but this benchmark doesn't help. (Incidentally I just prepared a class
at C++ and Beyond on benchmarking, and this benchmark makes a lot of the
mistakes described therein...)


Andrei

This should be more relevant then:

//fib.d
import std.datetime, std.stdio, std.variant;

auto fib(Int)()
{
        Int a = 1, b = 1;
        for(size_t i=0; i<100; i++){
                Int c = a + b;
                a = b;
                b = c;
        }
        return a;      
}

void main()
{
        writeln(benchmark!(fib!int, fib!long, fib!Variant)(10_000));
}


dmd -O -inline -release fib.d

Output:

[TickDuration(197), TickDuration(276), TickDuration(93370107)]

I'm horrified. Who was working on std.variant enhancements? Please chime in.

--
Dmitry Olshansky