Thread Settings
[Extended Qos Support]

The properties of a thread of execution. More...

Classes
struct	DDS_ThreadSettings_t
	The properties of a thread of execution. More...
Defines
#define	DDS_THREAD_SETTINGS_KIND_MASK_DEFAULT
	The mask of default thread options.
Typedefs
typedef DDS_UnsignedLong	DDS_ThreadSettingsKindMask
	A mask of which each bit is taken from DDS_ThreadSettingsKind.
Enumerations
enum	DDS_ThreadSettingsKind {   DDS_THREAD_SETTINGS_FLOATING_POINT,   DDS_THREAD_SETTINGS_STDIO,   DDS_THREAD_SETTINGS_REALTIME_PRIORITY,   DDS_THREAD_SETTINGS_PRIORITY_ENFORCE }
	A collection of flags used to configure threads of execution. More...
enum	DDS_ThreadSettingsCpuRotationKind {   DDS_THREAD_SETTINGS_CPU_NO_ROTATION,   DDS_THREAD_SETTINGS_CPU_RR_ROTATION }
	Determines how DDS_ThreadSettings_t::cpu_list affects processor affinity for thread-related QoS policies that apply to multiple threads. More...

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Detailed Description

The properties of a thread of execution.

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Define Documentation

#define DDS_THREAD_SETTINGS_KIND_MASK_DEFAULT

The mask of default thread options.

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Typedef Documentation

typedef DDS_UnsignedLong DDS_ThreadSettingsKindMask

A mask of which each bit is taken from DDS_ThreadSettingsKind.

See also:

DDS_ThreadSettings_t

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Enumeration Type Documentation

enum DDS_ThreadSettingsKind

A collection of flags used to configure threads of execution.

Not all of these options may be relevant for all operating systems.

See also:

DDS_ThreadSettingsKindMask

Enumerator:

DDS_THREAD_SETTINGS_FLOATING_POINT	Code executed within the thread may perform floating point operations.
DDS_THREAD_SETTINGS_STDIO	Code executed within the thread may access standard I/O.
DDS_THREAD_SETTINGS_REALTIME_PRIORITY	The thread will be schedule on a real-time basis.
DDS_THREAD_SETTINGS_PRIORITY_ENFORCE	Strictly enforce this thread's priority.

enum DDS_ThreadSettingsCpuRotationKind

Determines how DDS_ThreadSettings_t::cpu_list affects processor affinity for thread-related QoS policies that apply to multiple threads.

Controlling CPU Core Affinity for RTI Threads

Most thread-related QoS settings apply to a single thread (such as for the DDS_EventQosPolicy, DDS_DatabaseQosPolicy, and DDS_AsynchronousPublisherQosPolicy). However, the thread settings in the DDS_ReceiverPoolQosPolicy control every receive thread created. In this case, there are several schemes to map M threads to N processors; the rotation kind controls which scheme is used.

If DDS_ThreadSettings_t::cpu_list is empty, the rotation is irrelevant since no affinity adjustment will occur. Suppose instead that DDS_ThreadSettings_t::cpu_list = {0, 1} and that the middleware creates three receive threads: {A, B, C}. If DDS_ThreadSettings_t::cpu_rotation is DDS_THREAD_SETTINGS_CPU_NO_ROTATION, threads A, B and C will have the same processor affinities (0-1), and the OS will control thread scheduling within this bound. It is common to denote CPU affinities as a bitmask, where set bits represent allowed processors to run on. This mask is printed in hex, so a CPU core affinity of 0-1 can be represented by the mask 0x3.

If DDS_ThreadSettings_t::cpu_rotation is DDS_THREAD_SETTINGS_CPU_RR_ROTATION, each thread will be assigned in round-robin fashion to one of the processors in DDS_ThreadSettings_t::cpu_list; perhaps thread A to 0, B to 1, and C to 0. Note that the order in which internal middleware threads spawn is unspecified.

Not all of these options may be relevant for all operating systems.

Enumerator:

DDS_THREAD_SETTINGS_CPU_NO_ROTATION	Any thread controlled by this QoS can run on any listed processor, as determined by OS scheduling.
DDS_THREAD_SETTINGS_CPU_RR_ROTATION	Threads controlled by this QoS will be assigned one processor from the list in round-robin order.