Basic benchmark

[Denis Koroskin]

On Tue, 16 Dec 2008 06:23:14 +0300, Bill Baxter <wbaxter at gmail.com> wrote:

> On Tue, Dec 16, 2008 at 12:00 PM, Denis Koroskin <2korden at gmail.com>  
> wrote:
>> On Tue, 16 Dec 2008 05:28:16 +0300, Bill Baxter <wbaxter at gmail.com>  
>> wrote:
>>
>>> On Tue, Dec 16, 2008 at 11:09 AM, Andrei Alexandrescu
>>> <SeeWebsiteForEmail at erdani.org> wrote:
>>>>
>>>> Jarrett Billingsley wrote:
>>>>>
>>>>> On Sat, Dec 13, 2008 at 11:16 AM, Tomas Lindquist Olsen
>>>>> <tomas at famolsen.dk> wrote:
>>>>>>
>>>>>> I tried this out with Tango + DMD 1.033, Tango + LDC r847 and GCC
>>>>>> 4.3.2,
>>>>>> my
>>>>>> timings are as follows, best of three:
>>>>>>
>>>>>> $ dmd bench.d -O -release -inline
>>>>>> long arith:  55630 ms
>>>>>> nested loop:  5090 ms
>>>>>>
>>>>>>
>>>>>> $ ldc bench.d -O3 -release -inline
>>>>>> long arith:  13870 ms
>>>>>> nested loop:   120 ms
>>>>>>
>>>>>>
>>>>>> $ gcc bench.c -O3 -s -fomit-frame-pointer
>>>>>> long arith: 13600 ms
>>>>>> nested loop:  170 ms
>>>>>>
>>>>>>
>>>>>> My cpu is: Athlon64 X2 3800+
>>>>>>
>>>>>
>>>>> Go LDC!
>>>>>
>>>>> I hope bearophile will eventually understand that DMD is not good at
>>>>> optimizing code, and so comparing its output to GCC's is ultimately
>>>>> meaningless.
>>>>
>>>> I must have missed the memo. How is dmd not good at optimizing code?
>>>> Without
>>>> knowing many details about it, my understanding is that dmd performs
>>>> common
>>>> optimization reasonably well and that this particular problem has to  
>>>> do
>>>> with
>>>> the long division routine.
>>>
>>> It's pretty well proven that for floating point code, DMD tends to
>>> generate code about 50% slower than GCC.
>>>
>>> --bb
>>
>> But other than that it is pretty good.
>
> Yep, it's more than 100x faster than a straightforward Python ports of
> similar code, for instance.  (I did some benchmarking using a D port
> of the Laplace solver here http://www.scipy.org/PerformancePython  --
> I think bearophile did these comparisons again himself more recently,
> too).  There I saw DMD about 50% slower than g++.  But I've seen
> figures in the neighborhood of 50% come up a few times since then in
> other float-intensive benchmarks, like the raytracer that someone
> ported from c++.
>
> So it is certainly fast.  But one of the draws of D is precisely that,
> that it is fast.  If you're after code that runs as fast as possible,
> 50% slower than the competition is plenty justification for to go look
> elsewhere for your high-performance language.  A 50% hit may not
> really be relevant at the end of the day, but I know I used to avoid
> g++ like the plague because even it's output isn't that fast compared
> to MSVC++ or Intel's compiler, even though the difference is maybe
> only 10% or so.  I was working on interactive fluid simulation, so I
> wanted every bit of speed I could get out of the processor.  With
> interactive stuff, a 10% difference really can matter, I think.
>
>> And man, it is so fast!
>
> You mean compile times?
>
> --bb

Yeah.