Thread Settings

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

Classes
struct	DDS_ThreadSettings_t
	The properties of a thread of execution. More...

Macros
#define	DDS_THREAD_SETTINGS_KIND_MASK_DEFAULT
	The mask of default thread options. More...

Typedefs
typedef DDS_UnsignedLong	DDS_ThreadSettingsKindMask
	A mask of which each bit is taken from DDS_ThreadSettingsKind. More...

Enumerations
enum	DDS_ThreadSettingsKind {   DDS_THREAD_SETTINGS_FLOATING_POINT ,   DDS_THREAD_SETTINGS_STDIO ,   DDS_THREAD_SETTINGS_REALTIME_PRIORITY ,   DDS_THREAD_SETTINGS_PRIORITY_ENFORCE ,   DDS_THREAD_SETTINGS_CANCEL_ASYNCHRONOUS }
	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...

Detailed Description

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

Macro Definition Documentation

DDS_THREAD_SETTINGS_KIND_MASK_DEFAULT

#define DDS_THREAD_SETTINGS_KIND_MASK_DEFAULT

The mask of default thread options.

Typedef Documentation

DDS_ThreadSettingsKindMask

typedef DDS_UnsignedLong DDS_ThreadSettingsKindMask

A mask of which each bit is taken from DDS_ThreadSettingsKind.

See also

DDS_ThreadSettings_t

Enumeration Type Documentation

DDS_ThreadSettingsKind

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. Consult Platform Notes for additional details.

See also

DDS_ThreadSettingsKindMask

Enumerator
DDS_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.
DDS_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.
DDS_THREAD_SETTINGS_REALTIME_PRIORITY	The thread will be scheduled on a FIFO basis.
DDS_THREAD_SETTINGS_PRIORITY_ENFORCE	Strictly enforce this thread's priority.
DDS_THREAD_SETTINGS_CANCEL_ASYNCHRONOUS	Allows the thread to be cancelled without first reaching a cancellable state or cancellation point.

DDS_ThreadSettingsCpuRotationKind

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.

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 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. Refer to the Platform Notes for further information.

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.