Message du 28/03/11 19:52 De : "lcaminiti" A : boost@lists.boost.org Copie à : Objet : Re: [boost] [local] Help for the Alternatives section
Thomas Heller-7 wrote:
On Monday, March 28, 2011 07:03:46 PM lcaminiti wrote:
Thomas Heller-7 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...
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@sunshine ~/programming/local $ time ./add_phoenix 1e+12
real 0m6.648s user 0m6.643s sys 0m0.007s
This is not a fare comparison because add.cpp contains also local blocks and exits while add_boost_phoenix.cpp contains only local functions. The comparison should be made between add_boost_local.cpp and add_boost_phoenix.cpp (see below). The example names got a bit confusing and I will rename add.cpp to add_funciton_block_exit.cpp to avoid similar misunderstandings in the future.
Seriously? Did you even look at the files i attached?
Ooops... no, I didn't. I have files with the exact same name in sandbox/local/libs/local/examples so I assumed you attached these files...
Are you serious? Please write real benchmarks. By executing the resulting binaries of your code examples, the runtime is mainly dominated by process setup and the output on stdout.
Take a look here: https://svn.boost.org/svn/boost/trunk/libs/spirit/optimization/
I have looked at the files you have attached now and I see what you mean. Please scratch my previous benchmark numbers. I will run correct tests more along the lines of what you suggested.
Hi Lorenzo, To complete the performance comparison I will add a hand written test which should be used as reference implementation. for (size_t i = 0; i < v.size(); ++i) { sum += factor * num; } and a non-local functor so it can be used with foreach (which seems to perform better than the manual for (size_t i = 0; i < v.size(); ++i) struct non_local_add { // Unfortunately, extra code to manually program the functor class. local_add(double& _sum, int _factor): sum(_sum), factor(_factor) {} void operator()(double num) { // Body uses C++ statement syntax. sum += factor * num; std::cout << "Summed: " << sum << std::endl; } private: // Unfortunately, cannot bind so repeat variable types. double& sum; // Access `sum` by (non-constant) reference. const int factor; // Make `factor` constant. } ; int main() { double sum = 0.0; int factor = 10; std::vector v(3); v[0] = 1.0; v[1] = 2.0; v[2] = 3.0; non_local_add add(sum, factor); // Non Local functor `add` passed as template parameter. std::for_each(v.begin(), v.end(), add); std::cout << sum << std::endl; return 0; } In addition you can use Boost.Chrono so you measure exactly what you want to measure,i.e. the add instantiation + the foreach without setup and output. Best, Vicente P.S. I see that others have the same issue I have when posting in this list with the '<' and '>' symbols. From where you sent your last messages that results in html codes?