| Message ID | CAMPTgK2Fph+jQBtKQ+nHa7+BMdUCu=zT3dWaUO0pc7z=Xg8mWg@mail.gmail.com |
|---|---|
| State | New |
| Headers | show |
Hi, > This is patch is implement the std::thread::hardware_concurrency(). > Tested on pthreads-win32/winpthreads on windows OS, and on Linux/FreeBSD. Please send library patches to the library mailing list too. Also, always parch mainline first: actually in the latter the function is alread implemented, maybe something is missing for win32, please check, rediff, and resend. Thanks Paolo
On 10/31/2011 02:10 PM, niXman wrote:
> +#elif definen(_GLIBCXX_USE_GET_NPROCS)
Typo.
r~
On Oct 31, 2011, at 2:10 PM, niXman wrote:
> This is patch is implement the std::thread::hardware_concurrency().
[ general comment ] Ick, this isn't what I'd call clean. Maybe a porting header inclusion that defines a static inline pthread_num_processors_np when on those system that don't have it. With that then this routine could just use pthread_num_processors_np instead after including that porting header. Having dozens of files with cascades of #if went out of fashion back in the 1990s.
diff --git a/libstdc++-v3/src/thread.cc b/libstdc++-v3/src/thread.cc index 09e7fc5..3eacb06 100644 --- a/libstdc++-v3/src/thread.cc +++ b/libstdc++-v3/src/thread.cc @@ -112,10 +112,20 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION unsigned int thread::hardware_concurrency() noexcept { - int __n = _GLIBCXX_NPROCS; - if (__n < 0) - __n = 0; - return __n; + int count=0; +#if defined(PTW32_VERSION) || \ + (defined(__MINGW64_VERSION_MAJOR) && defined(_POSIX_THREADS)) || \ + defined(__hpux) + count=pthread_num_processors_np(); +#elif defined(__APPLE__) || defined(__FreeBSD__) + size_t size=sizeof(count); + sysctlbyname("hw.ncpu", &count, &size, NULL, 0); +#elif defined(_SC_NPROCESSORS_ONLN) + count=sysconf(_SC_NPROCESSORS_ONLN); +#elif definen(_GLIBCXX_USE_GET_NPROCS) + count=_GLIBCXX_NPROCS; +#endif + return (count>0)?count:0; } _GLIBCXX_END_NAMESPACE_VERSION