std.variant benchmark

[Gor Gyolchanyan]

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

Thank you for demonstrating my point. :-)

-- 
Bye,
Gor Gyolchanyan.
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