Thread Settings

The properties of a thread of execution. Consult Platform Notes for additional platform specific details. More...

Classes
class	DDS::ThreadSettings_t
	The properties of a thread of execution. More...

Enumerations
enum	DDS::ThreadSettingsKind : UINT32 {   DDS::ThreadSettingsKind::THREAD_SETTINGS_FLOATING_POINT,   DDS::ThreadSettingsKind::THREAD_SETTINGS_STDIO,   DDS::ThreadSettingsKind::THREAD_SETTINGS_REALTIME_PRIORITY,   DDS::ThreadSettingsKind::THREAD_SETTINGS_PRIORITY_ENFORCE,   DDS::ThreadSettingsKind::THREAD_SETTINGS_CANCEL_ASYNCHRONOUS,   DDS::ThreadSettingsKind::THREAD_SETTINGS_KIND_MASK_DEFAULT }
	A collection of flags used to configure threads of execution. More...
enum	DDS::ThreadSettingsCpuRotationKind : UINT32 {   DDS::ThreadSettingsCpuRotationKind::THREAD_SETTINGS_CPU_NO_ROTATION,   DDS::ThreadSettingsCpuRotationKind::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...

Detailed Description

The properties of a thread of execution. Consult Platform Notes for additional platform specific details.

Enumeration Type Documentation

ThreadSettingsKind

enum DDS::ThreadSettingsKind : UINT32

strong

A collection of flags used to configure threads of execution.

Not all of these options may be relevant for all operating systems. Consult Platform Notes for additional details.

Enumerator
THREAD_SETTINGS_FLOATING_POINT	Code executed within the thread may perform floating point operations. Currently applicable only for VxWorks platforms, where user callbacks use floating-point operations.
THREAD_SETTINGS_STDIO	Code executed within the thread may access standard I/O. Currently applicable only for VxWorks platforms, where user callbacks do standard I/O operations.
THREAD_SETTINGS_REALTIME_PRIORITY	The thread will be scheduled on a FIFO basis.
THREAD_SETTINGS_PRIORITY_ENFORCE	Strictly enforce this thread's priority.
THREAD_SETTINGS_CANCEL_ASYNCHRONOUS	Allows the thread to be cancelled without first reaching a cancellable state or cancellation point.
THREAD_SETTINGS_KIND_MASK_DEFAULT	The mask of default thread options.

ThreadSettingsCpuRotationKind

enum DDS::ThreadSettingsCpuRotationKind : UINT32

strong

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.

Controlling CPU Core Affinity is only relevant to the DDS::ReceiverPoolQosPolicy. It is ignored within other QoS policies that include DDS::ThreadSettings_t.

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 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 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. Refer to the Platform Notes for further information.

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