| /* |
| * kmp_wait_release.h -- Wait/Release implementation |
| * $Revision: 43417 $ |
| * $Date: 2014-08-26 14:06:38 -0500 (Tue, 26 Aug 2014) $ |
| */ |
| |
| |
| //===----------------------------------------------------------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is dual licensed under the MIT and the University of Illinois Open |
| // Source Licenses. See LICENSE.txt for details. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| |
| #ifndef KMP_WAIT_RELEASE_H |
| #define KMP_WAIT_RELEASE_H |
| |
| #include "kmp.h" |
| #include "kmp_itt.h" |
| |
| /*! |
| @defgroup WAIT_RELEASE Wait/Release operations |
| |
| The definitions and functions here implement the lowest level thread |
| synchronizations of suspending a thread and awaking it. They are used |
| to build higher level operations such as barriers and fork/join. |
| */ |
| |
| /*! |
| @ingroup WAIT_RELEASE |
| @{ |
| */ |
| |
| /*! |
| * The flag_type describes the storage used for the flag. |
| */ |
| enum flag_type { |
| flag32, /**< 32 bit flags */ |
| flag64, /**< 64 bit flags */ |
| flag_oncore /**< special 64-bit flag for on-core barrier (hierarchical) */ |
| }; |
| |
| /*! |
| * Base class for wait/release volatile flag |
| */ |
| template <typename P> |
| class kmp_flag { |
| volatile P * loc; /**< Pointer to the flag storage that is modified by another thread */ |
| flag_type t; /**< "Type" of the flag in loc */ |
| public: |
| typedef P flag_t; |
| kmp_flag(volatile P *p, flag_type ft) : loc(p), t(ft) {} |
| /*! |
| * @result the pointer to the actual flag |
| */ |
| volatile P * get() { return loc; } |
| /*! |
| * @result the flag_type |
| */ |
| flag_type get_type() { return t; } |
| // Derived classes must provide the following: |
| /* |
| kmp_info_t * get_waiter(kmp_uint32 i); |
| kmp_uint32 get_num_waiters(); |
| bool done_check(); |
| bool done_check_val(P old_loc); |
| bool notdone_check(); |
| P internal_release(); |
| P set_sleeping(); |
| P unset_sleeping(); |
| bool is_sleeping(); |
| bool is_sleeping_val(P old_loc); |
| */ |
| }; |
| |
| /* Spin wait loop that first does pause, then yield, then sleep. A thread that calls __kmp_wait_* |
| must make certain that another thread calls __kmp_release to wake it back up to prevent deadlocks! */ |
| template <class C> |
| static inline void __kmp_wait_template(kmp_info_t *this_thr, C *flag, int final_spin |
| USE_ITT_BUILD_ARG(void * itt_sync_obj) ) |
| { |
| // NOTE: We may not belong to a team at this point. |
| volatile typename C::flag_t *spin = flag->get(); |
| kmp_uint32 spins; |
| kmp_uint32 hibernate; |
| int th_gtid; |
| int tasks_completed = FALSE; |
| |
| KMP_FSYNC_SPIN_INIT(spin, NULL); |
| if (flag->done_check()) { |
| KMP_FSYNC_SPIN_ACQUIRED(spin); |
| return; |
| } |
| th_gtid = this_thr->th.th_info.ds.ds_gtid; |
| KA_TRACE(20, ("__kmp_wait_sleep: T#%d waiting for flag(%p)\n", th_gtid, flag)); |
| |
| // Setup for waiting |
| KMP_INIT_YIELD(spins); |
| |
| if (__kmp_dflt_blocktime != KMP_MAX_BLOCKTIME) { |
| // The worker threads cannot rely on the team struct existing at this point. |
| // Use the bt values cached in the thread struct instead. |
| #ifdef KMP_ADJUST_BLOCKTIME |
| if (__kmp_zero_bt && !this_thr->th.th_team_bt_set) |
| // Force immediate suspend if not set by user and more threads than available procs |
| hibernate = 0; |
| else |
| hibernate = this_thr->th.th_team_bt_intervals; |
| #else |
| hibernate = this_thr->th.th_team_bt_intervals; |
| #endif /* KMP_ADJUST_BLOCKTIME */ |
| |
| /* If the blocktime is nonzero, we want to make sure that we spin wait for the entirety |
| of the specified #intervals, plus up to one interval more. This increment make |
| certain that this thread doesn't go to sleep too soon. */ |
| if (hibernate != 0) |
| hibernate++; |
| |
| // Add in the current time value. |
| hibernate += TCR_4(__kmp_global.g.g_time.dt.t_value); |
| KF_TRACE(20, ("__kmp_wait_sleep: T#%d now=%d, hibernate=%d, intervals=%d\n", |
| th_gtid, __kmp_global.g.g_time.dt.t_value, hibernate, |
| hibernate - __kmp_global.g.g_time.dt.t_value)); |
| } |
| KMP_MB(); |
| |
| // Main wait spin loop |
| while (flag->notdone_check()) { |
| int in_pool; |
| |
| /* If the task team is NULL, it means one of things: |
| 1) A newly-created thread is first being released by __kmp_fork_barrier(), and |
| its task team has not been set up yet. |
| 2) All tasks have been executed to completion, this thread has decremented the task |
| team's ref ct and possibly deallocated it, and should no longer reference it. |
| 3) Tasking is off for this region. This could be because we are in a serialized region |
| (perhaps the outer one), or else tasking was manually disabled (KMP_TASKING=0). */ |
| kmp_task_team_t * task_team = NULL; |
| if (__kmp_tasking_mode != tskm_immediate_exec) { |
| task_team = this_thr->th.th_task_team; |
| if (task_team != NULL) { |
| if (!TCR_SYNC_4(task_team->tt.tt_active)) { |
| KMP_DEBUG_ASSERT(!KMP_MASTER_TID(this_thr->th.th_info.ds.ds_tid)); |
| __kmp_unref_task_team(task_team, this_thr); |
| } else if (KMP_TASKING_ENABLED(task_team, this_thr->th.th_task_state)) { |
| flag->execute_tasks(this_thr, th_gtid, final_spin, &tasks_completed |
| USE_ITT_BUILD_ARG(itt_sync_obj), 0); |
| } |
| } // if |
| } // if |
| |
| KMP_FSYNC_SPIN_PREPARE(spin); |
| if (TCR_4(__kmp_global.g.g_done)) { |
| if (__kmp_global.g.g_abort) |
| __kmp_abort_thread(); |
| break; |
| } |
| |
| // If we are oversubscribed, or have waited a bit (and KMP_LIBRARY=throughput), then yield |
| KMP_YIELD(TCR_4(__kmp_nth) > __kmp_avail_proc); |
| // TODO: Should it be number of cores instead of thread contexts? Like: |
| // KMP_YIELD(TCR_4(__kmp_nth) > __kmp_ncores); |
| // Need performance improvement data to make the change... |
| KMP_YIELD_SPIN(spins); |
| |
| // Check if this thread was transferred from a team |
| // to the thread pool (or vice-versa) while spinning. |
| in_pool = !!TCR_4(this_thr->th.th_in_pool); |
| if (in_pool != !!this_thr->th.th_active_in_pool) { |
| if (in_pool) { // Recently transferred from team to pool |
| KMP_TEST_THEN_INC32((kmp_int32 *)&__kmp_thread_pool_active_nth); |
| this_thr->th.th_active_in_pool = TRUE; |
| /* Here, we cannot assert that: |
| KMP_DEBUG_ASSERT(TCR_4(__kmp_thread_pool_active_nth) <= __kmp_thread_pool_nth); |
| __kmp_thread_pool_nth is inc/dec'd by the master thread while the fork/join |
| lock is held, whereas __kmp_thread_pool_active_nth is inc/dec'd asynchronously |
| by the workers. The two can get out of sync for brief periods of time. */ |
| } |
| else { // Recently transferred from pool to team |
| KMP_TEST_THEN_DEC32((kmp_int32 *) &__kmp_thread_pool_active_nth); |
| KMP_DEBUG_ASSERT(TCR_4(__kmp_thread_pool_active_nth) >= 0); |
| this_thr->th.th_active_in_pool = FALSE; |
| } |
| } |
| |
| // Don't suspend if KMP_BLOCKTIME is set to "infinite" |
| if (__kmp_dflt_blocktime == KMP_MAX_BLOCKTIME) |
| continue; |
| |
| // Don't suspend if there is a likelihood of new tasks being spawned. |
| if ((task_team != NULL) && TCR_4(task_team->tt.tt_found_tasks)) |
| continue; |
| |
| // If we have waited a bit more, fall asleep |
| if (TCR_4(__kmp_global.g.g_time.dt.t_value) < hibernate) |
| continue; |
| |
| KF_TRACE(50, ("__kmp_wait_sleep: T#%d suspend time reached\n", th_gtid)); |
| |
| flag->suspend(th_gtid); |
| |
| if (TCR_4(__kmp_global.g.g_done)) { |
| if (__kmp_global.g.g_abort) |
| __kmp_abort_thread(); |
| break; |
| } |
| // TODO: If thread is done with work and times out, disband/free |
| } |
| KMP_FSYNC_SPIN_ACQUIRED(spin); |
| } |
| |
| /* Release any threads specified as waiting on the flag by releasing the flag and resume the waiting thread |
| if indicated by the sleep bit(s). A thread that calls __kmp_wait_template must call this function to wake |
| up the potentially sleeping thread and prevent deadlocks! */ |
| template <class C> |
| static inline void __kmp_release_template(C *flag) |
| { |
| #ifdef KMP_DEBUG |
| // FIX ME |
| kmp_info_t * wait_thr = flag->get_waiter(0); |
| int target_gtid = wait_thr->th.th_info.ds.ds_gtid; |
| int gtid = TCR_4(__kmp_init_gtid) ? __kmp_get_gtid() : -1; |
| #endif |
| KF_TRACE(20, ("__kmp_release: T#%d releasing T#%d spin(%p)\n", gtid, target_gtid, flag->get())); |
| KMP_DEBUG_ASSERT(flag->get()); |
| KMP_FSYNC_RELEASING(flag->get()); |
| |
| typename C::flag_t old_spin = flag->internal_release(); |
| |
| KF_TRACE(100, ("__kmp_release: T#%d old spin(%p)=%d, set new spin=%d\n", |
| gtid, flag->get(), old_spin, *(flag->get()))); |
| |
| if (__kmp_dflt_blocktime != KMP_MAX_BLOCKTIME) { |
| // Only need to check sleep stuff if infinite block time not set |
| if (flag->is_sleeping_val(old_spin)) { |
| for (unsigned int i=0; i<flag->get_num_waiters(); ++i) { |
| kmp_info_t * waiter = flag->get_waiter(i); |
| int wait_gtid = waiter->th.th_info.ds.ds_gtid; |
| // Wake up thread if needed |
| KF_TRACE(50, ("__kmp_release: T#%d waking up thread T#%d since sleep spin(%p) set\n", |
| gtid, wait_gtid, flag->get())); |
| flag->resume(wait_gtid); |
| } |
| } else { |
| KF_TRACE(50, ("__kmp_release: T#%d don't wake up thread T#%d since sleep spin(%p) not set\n", |
| gtid, target_gtid, flag->get())); |
| } |
| } |
| } |
| |
| template <typename FlagType> |
| struct flag_traits {}; |
| |
| template <> |
| struct flag_traits<kmp_uint32> { |
| typedef kmp_uint32 flag_t; |
| static const flag_type t = flag32; |
| static inline flag_t tcr(flag_t f) { return TCR_4(f); } |
| static inline flag_t test_then_add4(volatile flag_t *f) { return KMP_TEST_THEN_ADD4_32((volatile kmp_int32 *)f); } |
| static inline flag_t test_then_or(volatile flag_t *f, flag_t v) { return KMP_TEST_THEN_OR32((volatile kmp_int32 *)f, v); } |
| static inline flag_t test_then_and(volatile flag_t *f, flag_t v) { return KMP_TEST_THEN_AND32((volatile kmp_int32 *)f, v); } |
| }; |
| |
| template <> |
| struct flag_traits<kmp_uint64> { |
| typedef kmp_uint64 flag_t; |
| static const flag_type t = flag64; |
| static inline flag_t tcr(flag_t f) { return TCR_8(f); } |
| static inline flag_t test_then_add4(volatile flag_t *f) { return KMP_TEST_THEN_ADD4_64((volatile kmp_int64 *)f); } |
| static inline flag_t test_then_or(volatile flag_t *f, flag_t v) { return KMP_TEST_THEN_OR64((volatile kmp_int64 *)f, v); } |
| static inline flag_t test_then_and(volatile flag_t *f, flag_t v) { return KMP_TEST_THEN_AND64((volatile kmp_int64 *)f, v); } |
| }; |
| |
| template <typename FlagType> |
| class kmp_basic_flag : public kmp_flag<FlagType> { |
| typedef flag_traits<FlagType> traits_type; |
| FlagType checker; /**< Value to compare flag to to check if flag has been released. */ |
| kmp_info_t * waiting_threads[1]; /**< Array of threads sleeping on this thread. */ |
| kmp_uint32 num_waiting_threads; /**< Number of threads sleeping on this thread. */ |
| public: |
| kmp_basic_flag(volatile FlagType *p) : kmp_flag<FlagType>(p, traits_type::t), num_waiting_threads(0) {} |
| kmp_basic_flag(volatile FlagType *p, kmp_info_t *thr) : kmp_flag<FlagType>(p, traits_type::t), num_waiting_threads(1) { |
| waiting_threads[0] = thr; |
| } |
| kmp_basic_flag(volatile FlagType *p, FlagType c) : kmp_flag<FlagType>(p, traits_type::t), checker(c), num_waiting_threads(0) {} |
| /*! |
| * param i in index into waiting_threads |
| * @result the thread that is waiting at index i |
| */ |
| kmp_info_t * get_waiter(kmp_uint32 i) { |
| KMP_DEBUG_ASSERT(i<num_waiting_threads); |
| return waiting_threads[i]; |
| } |
| /*! |
| * @result num_waiting_threads |
| */ |
| kmp_uint32 get_num_waiters() { return num_waiting_threads; } |
| /*! |
| * @param thr in the thread which is now waiting |
| * |
| * Insert a waiting thread at index 0. |
| */ |
| void set_waiter(kmp_info_t *thr) { |
| waiting_threads[0] = thr; |
| num_waiting_threads = 1; |
| } |
| /*! |
| * @result true if the flag object has been released. |
| */ |
| bool done_check() { return traits_type::tcr(*(this->get())) == checker; } |
| /*! |
| * @param old_loc in old value of flag |
| * @result true if the flag's old value indicates it was released. |
| */ |
| bool done_check_val(FlagType old_loc) { return old_loc == checker; } |
| /*! |
| * @result true if the flag object is not yet released. |
| * Used in __kmp_wait_template like: |
| * @code |
| * while (flag.notdone_check()) { pause(); } |
| * @endcode |
| */ |
| bool notdone_check() { return traits_type::tcr(*(this->get())) != checker; } |
| /*! |
| * @result Actual flag value before release was applied. |
| * Trigger all waiting threads to run by modifying flag to release state. |
| */ |
| FlagType internal_release() { |
| return traits_type::test_then_add4((volatile FlagType *)this->get()); |
| } |
| /*! |
| * @result Actual flag value before sleep bit(s) set. |
| * Notes that there is at least one thread sleeping on the flag by setting sleep bit(s). |
| */ |
| FlagType set_sleeping() { |
| return traits_type::test_then_or((volatile FlagType *)this->get(), KMP_BARRIER_SLEEP_STATE); |
| } |
| /*! |
| * @result Actual flag value before sleep bit(s) cleared. |
| * Notes that there are no longer threads sleeping on the flag by clearing sleep bit(s). |
| */ |
| FlagType unset_sleeping() { |
| return traits_type::test_then_and((volatile FlagType *)this->get(), ~KMP_BARRIER_SLEEP_STATE); |
| } |
| /*! |
| * @param old_loc in old value of flag |
| * Test whether there are threads sleeping on the flag's old value in old_loc. |
| */ |
| bool is_sleeping_val(FlagType old_loc) { return old_loc & KMP_BARRIER_SLEEP_STATE; } |
| /*! |
| * Test whether there are threads sleeping on the flag. |
| */ |
| bool is_sleeping() { return is_sleeping_val(*(this->get())); } |
| }; |
| |
| class kmp_flag_32 : public kmp_basic_flag<kmp_uint32> { |
| public: |
| kmp_flag_32(volatile kmp_uint32 *p) : kmp_basic_flag<kmp_uint32>(p) {} |
| kmp_flag_32(volatile kmp_uint32 *p, kmp_info_t *thr) : kmp_basic_flag<kmp_uint32>(p, thr) {} |
| kmp_flag_32(volatile kmp_uint32 *p, kmp_uint32 c) : kmp_basic_flag<kmp_uint32>(p, c) {} |
| void suspend(int th_gtid) { __kmp_suspend_32(th_gtid, this); } |
| void resume(int th_gtid) { __kmp_resume_32(th_gtid, this); } |
| int execute_tasks(kmp_info_t *this_thr, kmp_int32 gtid, int final_spin, int *thread_finished |
| USE_ITT_BUILD_ARG(void * itt_sync_obj), kmp_int32 is_constrained) { |
| return __kmp_execute_tasks_32(this_thr, gtid, this, final_spin, thread_finished |
| USE_ITT_BUILD_ARG(itt_sync_obj), is_constrained); |
| } |
| void wait(kmp_info_t *this_thr, int final_spin |
| USE_ITT_BUILD_ARG(void * itt_sync_obj)) { |
| __kmp_wait_template(this_thr, this, final_spin |
| USE_ITT_BUILD_ARG(itt_sync_obj)); |
| } |
| void release() { __kmp_release_template(this); } |
| }; |
| |
| class kmp_flag_64 : public kmp_basic_flag<kmp_uint64> { |
| public: |
| kmp_flag_64(volatile kmp_uint64 *p) : kmp_basic_flag<kmp_uint64>(p) {} |
| kmp_flag_64(volatile kmp_uint64 *p, kmp_info_t *thr) : kmp_basic_flag<kmp_uint64>(p, thr) {} |
| kmp_flag_64(volatile kmp_uint64 *p, kmp_uint64 c) : kmp_basic_flag<kmp_uint64>(p, c) {} |
| void suspend(int th_gtid) { __kmp_suspend_64(th_gtid, this); } |
| void resume(int th_gtid) { __kmp_resume_64(th_gtid, this); } |
| int execute_tasks(kmp_info_t *this_thr, kmp_int32 gtid, int final_spin, int *thread_finished |
| USE_ITT_BUILD_ARG(void * itt_sync_obj), kmp_int32 is_constrained) { |
| return __kmp_execute_tasks_64(this_thr, gtid, this, final_spin, thread_finished |
| USE_ITT_BUILD_ARG(itt_sync_obj), is_constrained); |
| } |
| void wait(kmp_info_t *this_thr, int final_spin |
| USE_ITT_BUILD_ARG(void * itt_sync_obj)) { |
| __kmp_wait_template(this_thr, this, final_spin |
| USE_ITT_BUILD_ARG(itt_sync_obj)); |
| } |
| void release() { __kmp_release_template(this); } |
| }; |
| |
| // Hierarchical 64-bit on-core barrier instantiation |
| class kmp_flag_oncore : public kmp_flag<kmp_uint64> { |
| kmp_uint64 checker; |
| kmp_info_t * waiting_threads[1]; |
| kmp_uint32 num_waiting_threads; |
| kmp_uint32 offset; /**< Portion of flag that is of interest for an operation. */ |
| bool flag_switch; /**< Indicates a switch in flag location. */ |
| enum barrier_type bt; /**< Barrier type. */ |
| kmp_info_t * this_thr; /**< Thread that may be redirected to different flag location. */ |
| #if USE_ITT_BUILD |
| void *itt_sync_obj; /**< ITT object that must be passed to new flag location. */ |
| #endif |
| char& byteref(volatile kmp_uint64* loc, size_t offset) { return ((char *)loc)[offset]; } |
| public: |
| kmp_flag_oncore(volatile kmp_uint64 *p) |
| : kmp_flag<kmp_uint64>(p, flag_oncore), num_waiting_threads(0), flag_switch(false) {} |
| kmp_flag_oncore(volatile kmp_uint64 *p, kmp_uint32 idx) |
| : kmp_flag<kmp_uint64>(p, flag_oncore), offset(idx), num_waiting_threads(0), flag_switch(false) {} |
| kmp_flag_oncore(volatile kmp_uint64 *p, kmp_uint64 c, kmp_uint32 idx, enum barrier_type bar_t, |
| kmp_info_t * thr |
| #if USE_ITT_BUILD |
| , void *itt |
| #endif |
| ) |
| : kmp_flag<kmp_uint64>(p, flag_oncore), checker(c), offset(idx), bt(bar_t), this_thr(thr) |
| #if USE_ITT_BUILD |
| , itt_sync_obj(itt) |
| #endif |
| , num_waiting_threads(0), flag_switch(false) {} |
| kmp_info_t * get_waiter(kmp_uint32 i) { |
| KMP_DEBUG_ASSERT(i<num_waiting_threads); |
| return waiting_threads[i]; |
| } |
| kmp_uint32 get_num_waiters() { return num_waiting_threads; } |
| void set_waiter(kmp_info_t *thr) { |
| waiting_threads[0] = thr; |
| num_waiting_threads = 1; |
| } |
| bool done_check_val(kmp_uint64 old_loc) { return byteref(&old_loc,offset) == checker; } |
| bool done_check() { return done_check_val(*get()); } |
| bool notdone_check() { |
| // Calculate flag_switch |
| if (this_thr->th.th_bar[bt].bb.wait_flag == KMP_BARRIER_SWITCH_TO_OWN_FLAG) |
| flag_switch = true; |
| if (byteref(get(),offset) != 1 && !flag_switch) |
| return true; |
| else if (flag_switch) { |
| this_thr->th.th_bar[bt].bb.wait_flag = KMP_BARRIER_SWITCHING; |
| kmp_flag_64 flag(&this_thr->th.th_bar[bt].bb.b_go, (kmp_uint64)KMP_BARRIER_STATE_BUMP); |
| __kmp_wait_64(this_thr, &flag, TRUE |
| #if USE_ITT_BUILD |
| , itt_sync_obj |
| #endif |
| ); |
| } |
| return false; |
| } |
| kmp_uint64 internal_release() { |
| kmp_uint64 old_val; |
| if (__kmp_dflt_blocktime == KMP_MAX_BLOCKTIME) { |
| old_val = *get(); |
| byteref(get(),offset) = 1; |
| } |
| else { |
| kmp_uint64 mask=0; |
| byteref(&mask,offset) = 1; |
| old_val = KMP_TEST_THEN_OR64((volatile kmp_int64 *)get(), mask); |
| } |
| return old_val; |
| } |
| kmp_uint64 set_sleeping() { |
| return KMP_TEST_THEN_OR64((kmp_int64 volatile *)get(), KMP_BARRIER_SLEEP_STATE); |
| } |
| kmp_uint64 unset_sleeping() { |
| return KMP_TEST_THEN_AND64((kmp_int64 volatile *)get(), ~KMP_BARRIER_SLEEP_STATE); |
| } |
| bool is_sleeping_val(kmp_uint64 old_loc) { return old_loc & KMP_BARRIER_SLEEP_STATE; } |
| bool is_sleeping() { return is_sleeping_val(*get()); } |
| void wait(kmp_info_t *this_thr, int final_spin |
| USE_ITT_BUILD_ARG(void * itt_sync_obj)) { |
| __kmp_wait_template(this_thr, this, final_spin |
| USE_ITT_BUILD_ARG(itt_sync_obj)); |
| } |
| void release() { __kmp_release_template(this); } |
| void suspend(int th_gtid) { __kmp_suspend_oncore(th_gtid, this); } |
| void resume(int th_gtid) { __kmp_resume_oncore(th_gtid, this); } |
| int execute_tasks(kmp_info_t *this_thr, kmp_int32 gtid, int final_spin, int *thread_finished |
| USE_ITT_BUILD_ARG(void * itt_sync_obj), kmp_int32 is_constrained) { |
| return __kmp_execute_tasks_oncore(this_thr, gtid, this, final_spin, thread_finished |
| USE_ITT_BUILD_ARG(itt_sync_obj), is_constrained); |
| } |
| }; |
| |
| /*! |
| @} |
| */ |
| |
| #endif // KMP_WAIT_RELEASE_H |