I have this small program here, which compares the call-overhead of methods from classes to structs. I guess this always has to be, because of the "polymorphism" of methods of objects.

Is there something I can do to improve on the performance of methods calls with classes?

please see the source here:
https://gist.github.com/1242911


thanks in advance

christian

You didn't call sw.reset() before calling sw.stop()!

On 9/26/11, Andrej Mitrovic <andrej.mitrovich@gmail.com> wrote:
> You didn't call sw.reset() before calling sw.stop()!
>
Ehh, I mean before sw.start().

In the class test reset the timer:
    {
        auto h = new HClass();
        sw.reset(); // <-
        sw.start();
    }

On Mon, 26 Sep 2011 14:14:09 -0400, Christian Köstlin <christian.koestlin@gmail.com> wrote:

> I have this small program here, which compares the call-overhead of methods from classes to structs. I guess this always has to be, because of the "polymorphism" of methods of objects.
>
> Is there something I can do to improve on the performance of methods calls with classes?
>
> please see the source here:
> https://gist.github.com/1242911

In addition to Andrej's information (call sw.reset()),  make *sure* you compile in -release mode, because in non -release mode, all object methods are followed by a call to Object's invariant, which is never inlined!  However, no invariants are called in release mode.

-Steve

On 09/26/2011 08:29 PM, Andrej Mitrovic wrote:
> In the class test reset the timer:
>      {
>          auto h = new HClass();
>          sw.reset(); //<-
>          sw.start();
>      }
thanks a lot ... i totally misused the stopwatch api.

i compiled with:
  dmd -release -O -inline -m64 -oftarget/dmd/structs_vs_classes experimental/structs_vs_classes.d
and
  gdc -O3 -inline -o target/gdc/structs_vs_classes experimental/structs_vs_classes.d

wich resulted in:
target/dmd/structs_vs_classes
time with struct: 11326 for 1
time with class: 11323 for 1

and
target/gdc/structs_vs_classes
time with struct: 4011 for 1
time with class: 6880 for 1

which is much better than my wrong measurements...

thanks for the answer!!!

christian

Christian K.:

> i totally misused the stopwatch api.

I have misused it the same way, the first time. If other people will find the same problem then it means its API has problems.

Bye,
bearophile

On Mon, 26 Sep 2011 15:58:48 -0400, bearophile <bearophileHUGS@lycos.com> wrote:

> Christian K.:
>
>> i totally misused the stopwatch api.
>
> I have misused it the same way, the first time. If other people will find the same problem then it means its API has problems.

Have you ever used a real stopwatch?  It works the same way :)  Start/stop does not reset the time to 0, it just adds more time to the total.  Reset clears to 0.

I think probably the documentation needs to be better.  The example also suggests start resets the stopwatch.

-Steve

On Mon, 26 Sep 2011 15:36:04 -0400, Christian Köstlin <christian.koestlin@gmail.com> wrote:

> On 09/26/2011 08:29 PM, Andrej Mitrovic wrote:
>> In the class test reset the timer:
>>      {
>>          auto h = new HClass();
>>          sw.reset(); //<-
>>          sw.start();
>>      }
> thanks a lot ... i totally misused the stopwatch api.
>
> i compiled with:
>    dmd -release -O -inline -m64 -oftarget/dmd/structs_vs_classes experimental/structs_vs_classes.d
> and
>    gdc -O3 -inline -o target/gdc/structs_vs_classes experimental/structs_vs_classes.d
>
> wich resulted in:
> target/dmd/structs_vs_classes
> time with struct: 11326 for 1
> time with class: 11323 for 1
>
> and
> target/gdc/structs_vs_classes
> time with struct: 4011 for 1
> time with class: 6880 for 1

use -frelease to disable invariant calls on gdc.

Very important!

-Steve

On 09/26/2011 10:30 PM, Steven Schveighoffer wrote:
> On Mon, 26 Sep 2011 15:58:48 -0400, bearophile
> <bearophileHUGS@lycos.com> wrote:
>
>> Christian K.:
>>
>>> i totally misused the stopwatch api.
>>
>> I have misused it the same way, the first time. If other people will
>> find the same problem then it means its API has problems.
>
> Have you ever used a real stopwatch? It works the same way :) Start/stop
> does not reset the time to 0, it just adds more time to the total. Reset
> clears to 0.
>
> I think probably the documentation needs to be better. The example also
> suggests start resets the stopwatch.
>
> -Steve
you are totally right ... it is the same as a real stopwatch ... so there should be no problem (i also used it correctly in another benchmark, but it was quite late and ...)

thanks

christian