tbb::internal::atomic_backoff Class Reference

Class that implements exponential backoff. More...

#include <tbb_machine.h>

Inheritance diagram for tbb::internal::atomic_backoff:

Collaboration diagram for tbb::internal::atomic_backoff:

Public Member Functions
	atomic_backoff ()
	atomic_backoff (bool)
void	pause ()
	Pause for a while. More...
bool	bounded_pause ()
	Pause for a few times and return false if saturated. More...
void	reset ()

Private Attributes
int32_t	count

Static Private Attributes
static const int32_t	LOOPS_BEFORE_YIELD = 16
	Time delay, in units of "pause" instructions. More...

Additional Inherited Members
Private Member Functions inherited from tbb::internal::no_copy
	no_copy (const no_copy &)=delete
	no_copy ()=default

Detailed Description

Class that implements exponential backoff.

See implementation of spin_wait_while_eq for an example.

Definition at line 345 of file tbb_machine.h.

Constructor & Destructor Documentation

atomic_backoff() [1/2]

tbb::internal::atomic_backoff::atomic_backoff ( )

inline

Definition at line 355 of file tbb_machine.h.

: count(1) {}

atomic_backoff() [2/2]

tbb::internal::atomic_backoff::atomic_backoff ( bool  )

inline

Definition at line 357 of file tbb_machine.h.

: count(1) { pause(); }

References pause().

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Member Function Documentation

bounded_pause()

bool tbb::internal::atomic_backoff::bounded_pause ( )

inline

Pause for a few times and return false if saturated.

Definition at line 372 of file tbb_machine.h.

                         {
        __TBB_Pause(count);
        if( count<LOOPS_BEFORE_YIELD ) {
            // Pause twice as long the next time.
            count*=2;
            return true;
        } else {
            return false;
        }
    }

References __TBB_Pause(), count, and LOOPS_BEFORE_YIELD.

Referenced by tbb::internal::prolonged_pause().

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pause()

void tbb::internal::atomic_backoff::pause ( )

inline

Pause for a while.

Definition at line 360 of file tbb_machine.h.

                 {
        if( count<=LOOPS_BEFORE_YIELD ) {
            __TBB_Pause(count);
            // Pause twice as long the next time.
            count*=2;
        } else {
            // Pause is so long that we might as well yield CPU to scheduler.
            __TBB_Yield();
        }
    }

References __TBB_Pause(), __TBB_Yield, count, and LOOPS_BEFORE_YIELD.

Referenced by __TBB_AtomicAND(), __TBB_AtomicOR(), tbb::internal::__TBB_FetchAndAddGeneric(), tbb::internal::__TBB_FetchAndStoreGeneric(), __TBB_LockByte(), tbb::internal::__TBB_MaskedCompareAndSwap(), tbb::internal::generic_scheduler::acquire_task_pool(), atomic_backoff(), tbb::internal::concurrent_vector_base_v3::helper::extend_segment_table(), tbb::interface5::fetch_and_and(), tbb::interface5::fetch_and_or(), tbb::spin_rw_mutex_v3::internal_acquire_reader(), tbb::spin_rw_mutex_v3::internal_acquire_writer(), tbb::internal::concurrent_vector_base_v3::internal_grow_to_at_least_with_result(), tbb::internal::mail_outbox::internal_pop(), tbb::spin_rw_mutex_v3::internal_upgrade(), tbb::internal::micro_queue::push(), tbb::interface5::spin_wait_until_and(), tbb::internal::spin_wait_until_eq(), tbb::strict_ppl::internal::micro_queue< Value >::spin_wait_until_my_turn(), tbb::internal::spin_wait_while(), tbb::internal::spin_wait_while_eq(), and tbb::interface5::spin_wait_while_geq().

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reset()

void tbb::internal::atomic_backoff::reset ( )

inline

Definition at line 383 of file tbb_machine.h.

                 {
        count = 1;
    }

References count.

Member Data Documentation

count

int32_t tbb::internal::atomic_backoff::count

private

Definition at line 350 of file tbb_machine.h.

Referenced by bounded_pause(), pause(), and reset().

LOOPS_BEFORE_YIELD

const int32_t tbb::internal::atomic_backoff::LOOPS_BEFORE_YIELD = 16

staticprivate

Time delay, in units of "pause" instructions.

Should be equal to approximately the number of "pause" instructions that take the same time as an context switch. Must be a power of two.

Definition at line 349 of file tbb_machine.h.

Referenced by bounded_pause(), and pause().

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

• tbb_machine.h