Re: [boost] [local] Help for the Alternatives section

Subject: Re: [boost] [local] Help for the Alternatives section
From: Lorenzo Caminiti (lorcaminiti_at_[hidden])
Date: 2011-04-03 13:26:20

On Sun, Apr 3, 2011 at 1:23 PM, Lorenzo Caminiti <lorcaminiti_at_[hidden]> wrote:
> On Mon, Mar 28, 2011 at 2:50 AM, Thomas Heller
> <thom.heller_at_[hidden]> wrote:
>> On Monday, March 28, 2011 05:25:13 AM Jeremy Maitin-Shepard wrote:
>>> On 03/26/2011 03:19 PM, Lorenzo Caminiti wrote:
>>> > Hello all,
>>> >
>>> > I am updating Boost.Local docs and I could use a some help in getting
>>> > the Alternatives section right
>>> >
>> http://svn.boost.org/svn/boost/sandbox/local/libs/local/doc/html/boost_local/Alternatives.html
>>>
>>> You might include compile time and run time benchmarks, information
>>> about error message quality, and polymorphic capabilities.
>>> Additionally, you might note that with C++0x local classes can be used
>>> with templates.
>>
>> Just did a quick test ... code is attached ...
>>
>> $ time g++  -O3 -I. -Wall -Wextra add.cpp -o add
>>
>> real    0m0.657s
>> user    0m0.583s
>> sys     0m0.067s
>>
>> $ time ./add
>> 1e+12
>>
>> real    0m35.641s
>> user    0m35.618s
>> sys     0m0.017s
>>
>> $ time g++ -O3 -I. -Wall -Wextra add_boost_phoenix.cpp -o add_phoenix
>>
>> real    0m3.385s
>> user    0m3.160s
>> sys     0m0.217s
>> thomas_at_sunshine ~/programming/local $ time ./add_phoenix
>> 1e+12
>>
>> real    0m6.648s
>> user    0m6.643s
>> sys     0m0.007s
>
> I have done an (hopefully more correct) benchmark of Boost.Local
> performances compared with the alternative methods -- please check my
> doing :)
>
> In summary:
> 1) Boost.Phoenix, global functors, and local functors run in ~15s.
> 2) Boost.Lambda runs in ~40s.
> 3) Boost.Local runs in ~53s.
> 4) I don't have a C++0x lambda compiler so I could not benchmark C++0x lambdas.
>
> I don't know why Boost.Lambda takes longer than 1). Boost.Local seems
> to take longer than 1) because of the extra virtual function call
> introduced by the trick that allows to pass the local struct as a
> template parameter -- I will follow up with another email to explain
> this point in detail.
>
> ANALYSIS
>
> The basic code looks like this (see attachments):
>
> #define N 10000
>
> int main() {
>    double sum = 0.0;
>    int factor = 10;
>
>    void BOOST_LOCAL_FUNCTION_PARAMS( (const double& num)
>            (bind& sum) (const bind& factor) ) {
>        sum += factor * num;
>    } BOOST_LOCAL_FUNCTION_NAME(add)
>
>    std::vector<double> v(N * 100);
>    std::fill(v.begin(), v.end(), 10);
>    for (size_t n = 0; n < N; ++n) {
>        std::for_each(v.begin(), v.end(), add);
>    }
>
>    std::cout << sum << std::endl;
>    return 0;
> }
>
> BOOST LOCAL
>
> $ time g++ -O3 -I../../.. -Wall -Wextra benchmark_boost_local.cpp
>
> real    0m8.330s
> user    0m1.166s
> sys     0m1.463s
>
> $ time ./a
> 1e+12
>
> real    0m52.735s
> user    0m52.109s
> sys     0m0.077s
>
> GLOBAL FUNCTOR
>
> $ time g++ -O3 -I../../.. -Wall -Wextra benchmark_global_functor.cpp
>
> real    0m5.302s
> user    0m0.573s
> sys     0m0.560s
>
> $ time ./a
> 1e+12
>
> real    0m15.167s
> user    0m14.499s
> sys     0m0.030s
>
> LOCAL FUNCTOR (manual for-loop instead of for_each)
>
> $ time g++ -O3 -I../../.. -Wall -Wextra benchmark_local_functor.cpp
>
> real    0m5.476s
> user    0m0.510s
> sys     0m0.730s
>
> $ time ./a
> 1e+12
>
> real    0m15.392s
> user    0m14.686s
> sys     0m0.108s
>
> BOOST LAMBDA
>
> $ time g++ -O3 -I../../.. -Wall -Wextra benchmark_boost_lambda.cpp
>
> real    0m6.631s
> user    0m0.792s
> sys     0m1.199s
>
> $ time ./a
> 1e+12
>
> real    0m39.855s
> user    0m38.905s
> sys     0m0.061s
>
> BOOST PHOENIX
>
> $ time g++ -O3 -I../../.. -Wall -Wextra benchmark_boost_phoenix.cpp
>
> real    0m14.004s
> user    0m3.761s
> sys     0m3.543s
>
> $ time ./a
> 1e+12
>
> real    0m15.727s
> user    0m14.921s
> sys     0m0.030s

The source files are attached.

-- 
Lorenzo