STL算法使用多核吗？

Question

Do the C++ STL algorithms use multiple-cores of the CPU under the hood for faster performance? If not, are there any recommended libraries to do what does STL does but with multiple cores, say using OpenMP? Or are there any switches one can specify during compilation with gcc instructing STL to use multiple cores

EDIT: I am using Intel Core i7 960 processors, on Ubuntu 10.10 with gcc 4.4

Answer 1

GNU libstdc++ seems to have a parallel mode that supports several parallelization features for STL:

http://gcc.gnu.org/onlinedocs/libstdc++/manual/parallel_mode.html

Answer 2

I know of no STL implementation that leverages multiple cores. Even if one does exist, you need to ensure that the added complexity ends up as a net benefit. The types of algorithms STL provides (sort, accumulate, etc.) benefit from parallelism only in fairly extreme circumstances (eg > 10 million elements). If you only leverage parallelism at the STL level, you are probably going to be disappointed in the results.

I would look at Intel's TBB (http://threadingbuildingblocks.org/) which provides a task-based parallelism framework. It encourages algorithm design that is amenable to task-based scheduling and not just a bunch of leaf functions (eg parallel_sort() although TBB does provide one).

Answer 3

The C++ standard neither requires nor prohibits parallel execution of standard algorithms.

There have been a number of parallel implementations. In addition to libstdc++ parallel mode (which was mostly based on MCSTL ) there are STAPL , and OMPTL (which is also included in CVMLCPP ). There has been a fair amount of other work, but development of libstdc++ parallel mode seems to have killed quite a few other projects.