What is crossplatform code snippet for getting totall cores amount in C++?

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Programatically detect number of physical processors/cores or if hyper-threading is active on Windows, Mac and Linux

I wonder if there is any crossplatform (std or boost based or even c) way to get totall number of cores in a crossplatform manner? (for linux Mac Os X and Windows)

You were the first to vote to close your own question? O_o – ildjarn Aug 28 '11 at 01:17 — ildjarn, Aug 28 '11 at 01:17

score 3 · Answer 1 · answered Aug 28 '11 at 01:04

You could use OpenMP's omp_get_max_threads () function. For g++, enable OpenMP with the -fopenmp directive. For MS Visual Studio enable it in project properties - configuration properties - C/C++ - language. Be aware that omp_get_max_threads () may return less than the actual number of hardware cores/threads if omp_set_num_threads () has been used to limit the number of threads an OpenMP parallel region is allowed to use (not an issue at program start). You should also be aware that for hyper threading CPUs omp_get_max_threads () doesn't return the number of hardware CPU cores, but of hardware threads the CPU supports (and the additional threads provided by hyper threading don't quite cut it).

Kornel Kisielewicz · Accepted Answer · 2011-08-28T01:14:23.460

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Oooh, you'll probably have to get down to assembly...

http://code.google.com/p/geekinfo/source/browse/trunk/

Or go boost:

boost::thread::hardware_concurrency(); // returns number of cores/HT/procs

edited Aug 28 '11 at 01:14

answered Aug 28 '11 at 00:39

Kornel Kisielewicz

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I don't think so; and since when is assembly language cross platform? – Razzupaltuff Aug 28 '11 at 01:05
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This code only works on win32 (uses `SetThreadAffinityMask` etc) – bdonlan Aug 28 '11 at 01:06
@krax11erx, the library itself is cross-platform, at least it claims so... http://code.google.com/p/geekinfo/ – Kornel Kisielewicz Aug 28 '11 at 01:12
@bdonlan - other systems are in other files of the library – Kornel Kisielewicz Aug 28 '11 at 01:14
And even then that's not cross-platform because not everyone runs IA32 or Amd64 compatible hardware. – Adam Hawes Aug 28 '11 at 01:15
@Adam: there's no such thing as perfect cross-platform. I guess the boost solution would be the most cross-platform... although quite heavy for the task at hand – Kornel Kisielewicz Aug 28 '11 at 01:17
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The boost method is standard in c++11 now: std::thread::hardware_concurrency() – Eloff Jan 28 '12 at 04:15

What is crossplatform code snippet for getting totall cores amount in C++?

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