#include <sys/qos.h>

sys/qos.h

@typedef qos_class_t @abstract An abstract thread quality of service (QOS) classification. @discussion Thread quality of service (QOS) classes are ordered abstract representations of the nature of work that is expected to be performed by a pthread, dispatch queue, or NSOperation. Each class specifies a maximum thread scheduling priority for that band (which may be used in combination with a relative priority offset within the band), as well as quality of service characteristics for timer latency, CPU throughput, I/O throughput, network socket traffic management behavior and more. A best effort is made to allocate available system resources to every QOS class. Quality of service degredation only occurs during system resource contention, proportionally to the QOS class. That said, QOS classes representing user-initiated work attempt to achieve peak throughput while QOS classes for other work attempt to achieve peak energy and thermal efficiency, even in the absence of contention. Finally, the use of QOS classes does not allow threads to supersede any limits that may be applied to the overall process.

includes: sys/cdefs.h, Availability.h

2 functions · 1 enum · 1 typedef · 1 macro

enum(anonymous)

underlying type unsigned int

QOS_CLASS_USER_INTERACTIVE	33
QOS_CLASS_USER_INITIATED	25
QOS_CLASS_DEFAULT	21
QOS_CLASS_UTILITY	17
QOS_CLASS_BACKGROUND	9
QOS_CLASS_UNSPECIFIED	0

typedefqos_class_t

typedef unsigned int qos_class_t;

macroQOS_MIN_RELATIVE_PRIORITY

@constant QOS_MIN_RELATIVE_PRIORITY @abstract The minimum relative priority that may be specified within a QOS class. These priorities are relative only within a given QOS class and meaningful only for the current process.

#define QOS_MIN_RELATIVE_PRIORITY (-15)

functionqos_class_self

__API_AVAILABLE(macos(10.10), ios(8.0))
qos_class_t qos_class_self(void)

@function qos_class_self @abstract Returns the requested QOS class of the current thread. @return One of the QOS class values in qos_class_t.

functionqos_class_main

__API_AVAILABLE(macos(10.10), ios(8.0))
qos_class_t qos_class_main(void)

@function qos_class_main @abstract Returns the initial requested QOS class of the main thread. @discussion The QOS class that the main thread of a process is created with depends on the type of process (e.g. application or daemon) and on how it has been launched. This function returns that initial requested QOS class value chosen by the system to enable propagation of that classification to matching work not executing on the main thread. @return One of the QOS class values in qos_class_t.