A wrapper for the Linux CPU_SET data structure. More...

#include <cpu_set.hpp>

Public Member Functions
	cpu_set ()

std::size_t	capacity () const
	Return the number of CPUs that can be stored in the cpu set. More...

bool	status (int cpu) const
	Returns true if cpu is included in the cpu set. More...

int	count () const
	Return the number of cpus included in the cpu set. More...

cpu_set &	reset ()
	Remove all cpus from the cpu set. More...

cpu_set &	set (int cpu)
	Add cpu to the cpu set. More...

cpu_set &	clear (int cpu)
	Remove cpu from the cpu set. More...

cpu_set &	set (int cpulo, int cpuhi)
	Add all the cpus in the [cpulo,cpuhi] range to the set. More...

cpu_set &	clear (int cpulo, int cpuhi)
	Remove all the cpus in the [cpulo,cpuhi] range from the set. More...

std::string	as_list_format () const
	Return the set in the list format representation. More...

Implement bitwise operations for cpu sets.
void	operator &= (cpu_set const &rhs)

void	operator\|= (cpu_set const &rhs)

void	operator^= (cpu_set const &rhs)

Comparison operators for cpu sets.
bool	operator== (cpu_set const &rhs) const

bool	operator!= (cpu_set const &rhs) const

Access the native implementation.
cpu_set_t *	native_handle ()

cpu_set_t const *	native_handle () const

Static Public Member Functions
static cpu_set	parse (std::string const &value)
	Interpret value as a cpu set in list format. More...

Private Member Functions
void	check_range (int cpu, char const *op) const
	Check that cpu is in range. More...

void	check_range (int cpulo, int cpuhi, char const *op) const
	Check that [cpulo,cpuhi] is in range. More...

Static Private Member Functions
static void	parse_error (std::string const &value)
	Raise an exception because the input to parse() is invalid. More...

Private Attributes
cpu_set_t	set_

Detailed Description

A wrapper for the Linux CPU_SET data structure.

Setting CPU affinity can help improve the predictability of our system. Typically different threads are assigned to different processors and in extreme cases no threads share the same core. The cpu sets are also typically configured using the "List Format" as described in cpuset(7). Briefly this format is:

cpuset ::= range[,cpuset] range ::= (number|number-number) number ::= a positive integer

So one can specify a cpu_set as "1,2,3" (cpus 1, 2 and 3), or "1-15" (cpus from 1 to 15), or "0-4,10,12-14" (cpus 0 to 4, 10 and 12 to 14).

The iostream operators (used for tests, and conversions everywhere) use this format.

TODO(#151) this is a portability problem. Many platforms can specify cpu affinity, but they all use different constructs for it. TODO(#152) we only support up to CPU_SETSIZE cpus, it is possible to control more CPUs in Linux, but the application that has access to more than 1024 cpus is rare indeed.

Definition at line 37 of file cpu_set.hpp.

Constructor & Destructor Documentation

◆ cpu_set()

jb::cpu_set::cpu_set ( )

inline

Definition at line 39 of file cpu_set.hpp.

References set_.

Member Function Documentation

◆ as_list_format()

std::string jb::cpu_set::as_list_format ( ) const

Return the set in the list format representation.

Definition at line 55 of file cpu_set.cpp.

References capacity(), and status().

Referenced by YAML::convert< jb::cpu_set >::encode(), operator!=(), and jb::operator<<().

◆ capacity()

std::size_t jb::cpu_set::capacity ( ) const

inline

Return the number of CPUs that can be stored in the cpu set.

Definition at line 45 of file cpu_set.hpp.

Referenced by as_list_format(), BOOST_AUTO_TEST_CASE(), and check_range().

◆ check_range() [1/2]

void jb::cpu_set::check_range	(	int	cpu,
		char const *	op
	)		const

private

Check that cpu is in range.

Exceptions

std::out_of_range if the argument is out of range.

Definition at line 75 of file cpu_set.cpp.

References capacity().

Referenced by clear(), native_handle(), and set().

◆ check_range() [2/2]

void jb::cpu_set::check_range	(	int	cpulo,
		int	cpuhi,
		char const *	op
	)		const

private

Check that [cpulo,cpuhi] is in range.

Exceptions

std::out_of_range if the arguments are out of range.

Definition at line 85 of file cpu_set.cpp.

References capacity().

◆ clear() [1/2]

cpu_set& jb::cpu_set::clear ( int cpu )

inline

Remove cpu from the cpu set.

Definition at line 73 of file cpu_set.hpp.

References check_range(), and set_.

Referenced by BOOST_AUTO_TEST_CASE().

◆ clear() [2/2]

jb::cpu_set & jb::cpu_set::clear	(	int	cpulo,
		int	cpuhi
	)

Remove all the cpus in the [cpulo,cpuhi] range from the set.

Definition at line 16 of file cpu_set.cpp.

References check_range(), and set_.

◆ count()

int jb::cpu_set::count ( ) const

inline

Return the number of cpus included in the cpu set.

Definition at line 55 of file cpu_set.hpp.

References set_.

Referenced by BOOST_AUTO_TEST_CASE().

◆ native_handle() [1/2]

cpu_set_t* jb::cpu_set::native_handle ( )

inline

Definition at line 127 of file cpu_set.hpp.

References set_.

◆ native_handle() [2/2]

cpu_set_t const* jb::cpu_set::native_handle ( ) const

inline

Definition at line 130 of file cpu_set.hpp.

References check_range(), parse_error(), and set_.

◆ operator &=()

void jb::cpu_set::operator&= ( cpu_set const & rhs )

inline

Definition at line 89 of file cpu_set.hpp.

References set_.

◆ operator!=()

bool jb::cpu_set::operator!= ( cpu_set const & rhs ) const

inline

Definition at line 108 of file cpu_set.hpp.

References as_list_format(), and parse().

◆ operator==()

bool jb::cpu_set::operator== ( cpu_set const & rhs ) const

inline

Definition at line 104 of file cpu_set.hpp.

References set_.

◆ operator^=()

void jb::cpu_set::operator^= ( cpu_set const & rhs )

inline

Definition at line 95 of file cpu_set.hpp.

References set_.

◆ operator|=()

void jb::cpu_set::operator|= ( cpu_set const & rhs )

inline

Definition at line 92 of file cpu_set.hpp.

References set_.

◆ parse()

jb::cpu_set jb::cpu_set::parse ( std::string const & value )

static

Interpret value as a cpu set in list format.

Definition at line 24 of file cpu_set.cpp.

References parse_error(), set(), and jb::strtonum().

Referenced by BOOST_AUTO_TEST_CASE(), YAML::convert< jb::cpu_set >::decode(), operator!=(), and jb::operator>>().

◆ parse_error()

void jb::cpu_set::parse_error ( std::string const & value )

staticprivate

Raise an exception because the input to parse() is invalid.

Definition at line 94 of file cpu_set.cpp.

Referenced by native_handle(), and parse().

◆ reset()

cpu_set& jb::cpu_set::reset ( )

inline

Remove all cpus from the cpu set.

Definition at line 60 of file cpu_set.hpp.

References set_.

◆ set() [1/2]

cpu_set& jb::cpu_set::set ( int cpu )

inline

Add cpu to the cpu set.

Definition at line 66 of file cpu_set.hpp.

References check_range(), and set_.

Referenced by BOOST_AUTO_TEST_CASE(), and parse().

◆ set() [2/2]

jb::cpu_set & jb::cpu_set::set	(	int	cpulo,
		int	cpuhi
	)

Add all the cpus in the [cpulo,cpuhi] range to the set.

Definition at line 8 of file cpu_set.cpp.

References check_range(), and set_.

◆ status()

bool jb::cpu_set::status ( int cpu ) const

inline

Returns true if cpu is included in the cpu set.

Definition at line 50 of file cpu_set.hpp.

References set_.

Referenced by as_list_format(), and BOOST_AUTO_TEST_CASE().

Member Data Documentation

◆ set_

cpu_set_t jb::cpu_set::set_

private

Definition at line 156 of file cpu_set.hpp.

Referenced by clear(), count(), cpu_set(), native_handle(), operator &=(), operator==(), operator^=(), operator|=(), reset(), set(), and status().

The documentation for this class was generated from the following files:

jb/cpu_set.hpp
jb/cpu_set.cpp

Public Member Functions

Static Public Member Functions

Private Member Functions

Static Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ cpu_set()

Member Function Documentation

◆ as_list_format()

◆ capacity()

◆ check_range() [1/2]

◆ check_range() [2/2]

◆ clear() [1/2]

◆ clear() [2/2]

◆ count()

◆ native_handle() [1/2]

◆ native_handle() [2/2]

◆ operator &=()

◆ operator!=()

◆ operator==()

◆ operator^=()

◆ operator|=()

◆ parse()

◆ parse_error()

◆ reset()

◆ set() [1/2]

◆ set() [2/2]

◆ status()

Member Data Documentation

◆ set_