20 General utilities library [utilities]

20.18 Execution policies [execpol]

20.18.1 In general [execpol.general]

1
#
Subclause [execpol] describes classes that are execution policy types.
An object of an execution policy type indicates the kinds of parallelism allowed in the execution of an algorithm and expresses the consequent requirements on the element access functions.
[ Example
: 
using namespace std;
vector<int> v = /* ... */;

// standard sequential sort
sort(v.begin(), v.end());

// explicitly sequential sort
sort(execution::seq, v.begin(), v.end());

// permitting parallel execution
sort(execution::par, v.begin(), v.end());

// permitting vectorization as well
sort(execution::par_unseq, v.begin(), v.end());
— end example
 ]
[ Note
:
Because different parallel architectures may require idiosyncratic parameters for efficient execution, implementations may provide additional execution policies to those described in this standard as extensions.
— end note
 ]