static inline void __pmp_thread_wake (pmp_thread_t *thread)
{
int32_t sync = __pmp_atomic_cmpxchg32(&thread->sync, PMP_SYNC_IDLE,
PMP_SYNC_UNBLOCKED);
assert(sync != PMP_SYNC_UNBLOCKED);
if (sync == PMP_SYNC_BLOCKED) {
__pmp_debug(PMP_DEBUG_THREAD, "thread global_id %d is being signaled\n",
thread->global_id);
thread->sync = PMP_SYNC_IDLE;
assert(thread->tid != -1);
__pmp_sample(PMP_PROFILE_THREAD_RESCHEDULE);
#if (defined PMP_USE_PTHREAD_SIGNALS)
if (pthread_kill(thread->pthread_id, SIGPMP) != 0) {
__pmp_fatal("unable to wake thread using pthread_kill\n");
}
#elif (defined PMP_NO_NPTL)
if (kill(thread->tid, SIGPMP) != 0) {
__pmp_fatal("unable to wake thread using kill\n");
}
#else
if (tkill(thread->tid, SIGPMP) != 0) {
__pmp_fatal("unable to wake thread using tkill\n");
}
#endif
}
else {
__pmp_debug(PMP_DEBUG_THREAD, "thread global_id %d is woken\n",
thread->global_id);
}
}
void __pmp_thread_create_main (void)
{
pmp_thread_t *thread = __pmp_get_main_thread();
int global_id;
global_id = __pmp_idstack_pop(&__pmp_manager.idstack);
assert(global_id == 0);
thread->pthread_id = pthread_self();
#ifdef PMP_NO_NPTL
thread->tid = getpid();
#else
thread->tid = gettid();
#endif
thread->local_id = 0;
#ifndef PMP_NO_TLS
#ifdef PMP_TLS_THREAD
__pmp_tls_current_thread = thread;
#endif
#ifdef PMP_TLS_LOCAL_ID
__pmp_tls_current_local_id = 0;
#endif
#ifdef PMP_TLS_GLOBAL_ID
__pmp_tls_current_global_id = thread->global_id;
#endif
#endif
#ifdef PMP_USE_PTHREAD_SIGNALS
if (pthread_sigmask(SIG_BLOCK, &__pmp_manager.mask_block_sigpmp,
NULL) != 0) {
__pmp_fatal("unable to set thread-specific sigmask\n");
}
#else
if (sigprocmask(SIG_BLOCK, &__pmp_manager.mask_block_sigpmp, NULL) != 0) {
__pmp_fatal("unable to set thread-specific sigmask\n");
}
#endif
if (pthread_setspecific(__pmp_manager.thread_key, (void *) thread) != 0) {
__pmp_fatal("unable to set thread-specific data\n");
}
__pmp_thread_bind(thread); /* early master bind */
__pmp_debug(PMP_DEBUG_THREAD, "created main thread global_id %d\n",
thread->global_id);
__pmp_debug(PMP_DEBUG_THREAD,
"__pmp_thread_create_main: tid=%d, pthread_id=0x%08x "
"global_id=%d, local_id=%d\n",
(int) thread->tid, (int) thread->pthread_id,
(int) thread->global_id, (int) thread->local_id);
}
static inline void __pmp_scheduler_sample (int sched)
{
#ifdef PMP_PROFILE
switch (sched) {
case PMP_SCHED_STATIC: {
__pmp_sample(PMP_PROFILE_SCHED_STATIC);
break;
}
case PMP_SCHED_STATIC_EVEN: {
__pmp_sample(PMP_PROFILE_SCHED_STATIC_EVEN);
break;
}
case PMP_SCHED_DYNAMIC: {
__pmp_sample(PMP_PROFILE_SCHED_DYNAMIC);
break;
}
case PMP_SCHED_GUIDED: {
__pmp_sample(PMP_PROFILE_SCHED_GUIDED);
break;
}
case PMP_SCHED_ORDERED_STATIC: {
__pmp_sample(PMP_PROFILE_SCHED_ORDERED_STATIC);
break;
}
case PMP_SCHED_ORDERED_STATIC_EVEN: {
__pmp_sample(PMP_PROFILE_SCHED_ORDERED_STATIC_EVEN);
break;
}
case PMP_SCHED_ORDERED_DYNAMIC: {
__pmp_sample(PMP_PROFILE_SCHED_ORDERED_DYNAMIC);
break;
}
case PMP_SCHED_ORDERED_GUIDED: {
__pmp_sample(PMP_PROFILE_SCHED_ORDERED_GUIDED);
break;
}
default: {
__pmp_fatal("unknown dynamic scheduling type %d\n", sched);
break;
}
}
#endif
}
static inline int __pmp_schedule_next (int global_id, int64_t *lowerp,
int64_t *upperp, int64_t *incp)
{
pmp_thread_t *thread = __pmp_get_thread(global_id);
int team_size = __pmp_get_team_size(thread->team);
int64_t iteration = thread->iteration;
pmp_local_id_t local_id = thread->local_id;
pmp_loop_t *loop = thread->loop;
assert(loop != NULL);
assert(local_id < team_size);
if (team_size == 1) {
if (iteration == 0) {
*lowerp = loop->lower;
*upperp = loop->upper;
*incp = loop->inc;
thread->ticket_number = loop->lower;
thread->iteration = 1;
__pmp_loop_analyser(thread, loop->sched, global_id, local_id,
loop->lower, loop->upper,
*lowerp, *upperp, *incp, 0, 0);
return 1;
}
else {
assert(iteration == 1);
__pmp_loop_free(thread);
return 0;
}
}
else {
int sched = loop->sched;
int64_t lower = loop->lower;
int64_t upper = loop->upper;
int64_t inc = loop->inc;
int64_t chunk = loop->chunk;
switch (sched) {
case PMP_SCHED_STATIC:
case PMP_SCHED_ORDERED_STATIC: {
/* NOTE: setting a small value of chunk causes (unnecessary) iteration
* through this code. If the chunk is ignored, the code degenerates
* into the static even case (which is the default). */
int64_t size = (upper - lower) / inc + 1;
int64_t size_per_thread = ((size - 1) / team_size + 1) * inc;
int64_t thread_lower = lower + (local_id * size_per_thread);
int64_t thread_upper = thread_lower + size_per_thread - inc;
int64_t this_lower = thread_lower + (iteration * chunk * inc);
int64_t this_upper = this_lower + (chunk - 1) * inc;
thread_upper = LOOPMIN(inc, thread_upper, upper);
this_upper = LOOPMIN(inc, this_upper, thread_upper);
if ((inc >= 0) ? (this_lower > thread_upper) :
(this_lower < thread_upper)) {
__pmp_loop_free(thread);
return 0;
}
else {
*incp = inc;
*lowerp = this_lower;
*upperp = this_upper;
thread->ticket_number = this_lower;
thread->iteration++;
__pmp_loop_analyser(thread, sched, global_id, local_id, lower, upper,
*lowerp, *upperp, *incp, 0, 0);
return 1;
}
/* NOT REACHED */
break;
}
case PMP_SCHED_STATIC_EVEN:
case PMP_SCHED_ORDERED_STATIC_EVEN: {
if (iteration == 0) {
int64_t size = (upper - lower) / inc + 1;
int64_t thread_lower;
int64_t thread_upper;
if (!__pmp_get_param()->static_fair) {
int64_t size_per_thread = ((size - 1) / team_size + 1) * inc;
thread_lower = lower + (local_id * size_per_thread);
thread_upper = thread_lower + size_per_thread - inc;
}
else {
int64_t chunk = size / team_size;
int64_t remainder = size - (chunk * team_size);
int64_t index = MIN(local_id, remainder) * (chunk + 1);
if (local_id > remainder) {
index += (local_id - remainder) * chunk;
}
thread_lower = lower + (index * inc);
chunk += (local_id < remainder);
thread_upper = thread_lower + (chunk - 1) * inc;
}
thread_upper = LOOPMIN(inc, thread_upper, upper);
if ((inc >= 0) ? (thread_lower > thread_upper) :
(thread_lower < thread_upper)) {
__pmp_loop_free(thread);
return 0;
}
else {
*incp = inc;
*lowerp = thread_lower;
*upperp = thread_upper;
thread->ticket_number = thread_lower;
thread->iteration++;
__pmp_loop_analyser(thread, sched, global_id, local_id,
lower, upper, *lowerp, *upperp,
*incp, 0, 0);
return 1;
}
}
else {
assert(iteration == 1);
__pmp_loop_free(thread);
return 0;
}
/* NOT REACHED */
break;
}
case PMP_SCHED_DYNAMIC:
case PMP_SCHED_ORDERED_DYNAMIC: {
int64_t stride = inc * chunk;
#if __WORDSIZE == 64
int64_t current = __pmp_atomic_xadd64(&loop->current, stride);
#else
/* TODO: the atomic xadd64 is a problem for 32-bit compilation */
/* the workaround below is just to do a 32-bit atomic add */
int64_t current;
current = (int64_t) __pmp_atomic_xadd32((int32_t *) &loop->current,
(int32_t) stride);
#endif
if ((inc >= 0) ? (current > upper) : (current < upper)) {
__pmp_loop_free(thread);
return 0;
}
else {
*incp = inc;
*lowerp = current;
*upperp = *lowerp + stride - inc;
*upperp = LOOPMIN(inc, upper, *upperp);
thread->ticket_number = current;
thread->iteration++;
__pmp_loop_analyser(thread, sched, global_id, local_id, lower, upper,
*lowerp, *upperp, *incp, 0, 0);
return 1;
}
/* NOT REACHED */
break;
}
case PMP_SCHED_GUIDED:
case PMP_SCHED_ORDERED_GUIDED: {
/* NOTE: guided scheduling uses a heuristic to choose a good
* chunk size to divide up the remaining iterations amongst
* the team (subject to a minimum). An exact implementation of
* this would require a lock on the loop data. However, the
* heuristic can be approximated using (possibly) stale values
* and this should be good enough. The value of "remaining"
* is monotonically decreasing. The worst that could happen
* is that an update to loop->chunk is lost slightly unbalancing
* the distribution. The most important point is that loop->current
* is maintained atomically. */
/* UPDATE: if cmpxchg64 is available then this is used to protect
* the update of loop->chunk. This is fairly cunning, and makes
* the chunk update more accurate in this case! */
int64_t min_chunk = loop->min_chunk;
int64_t remaining = upper - loop->current + 1; /* estimate */
int64_t my_chunk = MAX(min_chunk, MIN(chunk, remaining));/* estimate */
int64_t stride = inc * my_chunk;
#if __WORDSIZE == 64
int64_t current = __pmp_atomic_xadd64(&loop->current, stride);
#else
/* TODO: the atomic xadd64 is a problem for 32-bit compilation */
/* the workaround below is just to do a 32-bit atomic add */
int64_t current = __pmp_atomic_xadd32((int32_t *) &loop->current,
(int32_t) stride);
#endif
assert(stride != 0);
#ifdef SUPER_DEBUG
if (Enabled_Libomp_Loop_Debug)
__pmp_debug("LOOPS_DEBUG", "__pmp_schedule_next: global_id=%d, "
"remaining=%d, my_chunk=%d, stride=%d, current=%d\n",
global_id, remaining, my_chunk, stride, current);
#endif
if ((inc >= 0) ? (current > upper) : (current < upper)) {
__pmp_loop_free(thread);
return 0;
}
else {
pmp_param_t *param = __pmp_get_param();
int64_t my_upper = LOOPMIN(inc, upper, current + stride - inc);
int64_t new_chunk;
int64_t divisor;
remaining = upper - my_upper; /* estimate */
divisor = team_size * param->guided_chunk_divisor;
new_chunk = (remaining + divisor - 1) / divisor;
new_chunk = MIN(param->guided_chunk_max, new_chunk);
new_chunk = MAX(min_chunk, new_chunk);
#if __WORDSIZE == 64
(void) __pmp_atomic_cmpxchg64(&loop->chunk, chunk, new_chunk);
#else
loop->chunk = new_chunk; /* estimate */
#endif
*incp = inc;
*lowerp = current;
*upperp = my_upper;
thread->ticket_number = current;
thread->iteration++;
__pmp_loop_analyser(thread, sched, global_id, local_id, lower, upper,
*lowerp, *upperp, *incp, 0, 0);
return 1;
}
/* NOT REACHED */
break;
}
default: {
__pmp_fatal("unknown dynamic scheduling type %d\n", sched);
break;
}
}
/* NOT REACHED */
assert(0);
__pmp_loop_free(thread);
return 0;
}
/* NOT REACHED */
}
static inline void __pmp_static_init (int global_id, int sched,
int64_t *lowerp, int64_t *upperp,
int64_t *stridep,
int64_t inc, int64_t chunk)
{
/* NOTE: chunk parameter is undefined/unused for static even scheduling */
pmp_thread_t *thread = __pmp_get_thread(global_id);
int team_size = __pmp_get_team_size(thread->team);
int64_t loop_lower = *lowerp;
int64_t loop_upper = *upperp;
int64_t lower;
int64_t upper;
assert(team_size > 0);
if (chunk <= 0) {
if (thread->global_id == 0)
__pmp_warning("Chunk size is non-positive, set to default '1'\n");
chunk = 1;
}
if (team_size == 1) {
*stridep = (inc > 0) ? (loop_upper - loop_lower + 1) :
(loop_upper - loop_lower - 1);
}
else {
pmp_local_id_t local_id = thread->local_id;
int64_t stride;
switch (sched) {
case PMP_SCHED_STATIC_EVEN: {
int64_t size = (loop_upper - loop_lower) / inc + 1;
assert(size >= 0);
if (!__pmp_get_param()->static_fair) {
/* The size is divided by the team_size and rounded up to give
* the chunk size. Chunks of this size are assigned to threads
* in increased local_id order. If the division was not exact
* then the last thread will have fewer iterations, and possibly
* none at all. */
chunk = (size + team_size - 1) / team_size;
lower = loop_lower + (local_id * chunk * inc);
}
else {
/* The size is divided by the team_size and rounded down to
* give the chunk. Each thread will have at least this many
* iterations. If the division was not exact then the remainder
* iterations are scheduled across the threads in increasing
* thread order. Note that the difference between the minimum
* and maximum number of iterations assigned to the threads
* across the team is at most 1. The maximum number of iterations
* assigned to a thread (the worst case path through the schedule)
* is the same as for default behavior. */
int64_t remainder;
int64_t index;
chunk = size / team_size;
remainder = size - (chunk * team_size);
index = MIN(local_id, remainder) * (chunk + 1);
if (local_id > remainder) {
index += (local_id - remainder) * chunk;
}
lower = loop_lower + (index * inc);
chunk += (local_id < remainder);
}
if ((inc >= 0) ? (lower <= loop_upper) : (lower >= loop_upper)) {
upper = LOOPMIN(inc, lower + (chunk - 1) * inc, loop_upper);
stride = size * inc;
}
else {
/* If the entire set of iterations falls out of the loop bounds
* then arrange for a non-iterating loop which will not trigger
* the LASTPRIVATE check made by the compiler. This means that
* the final value of the loop induction variable must not exceed
* the loop upper bound. */
lower = loop_lower - inc;
upper = lower - inc;
stride = inc;
}
__pmp_loop_analyser(thread, sched, global_id, local_id,
loop_lower, loop_upper,
lower, upper, inc, chunk, stride);
break;
}
case PMP_SCHED_STATIC: {
stride = chunk * inc;
lower = loop_lower + (local_id * stride);
if ((inc >= 0) ? (lower <= loop_upper) : (lower >= loop_upper)) {
upper = LOOPMIN(inc, lower + (chunk - 1) * inc, loop_upper);
stride *= team_size;
}
else {
/* If the entire set of iterations falls out of the loop bounds
* then arrange for a non-iterating loop which will not trigger
* the LASTPRIVATE check made by the compiler. This means that
* the final value of the loop induction variable must not exceed
* the loop upper bound. */
lower = loop_lower - inc;
upper = lower - inc;
stride = inc;
}
__pmp_loop_analyser(thread, sched, global_id, local_id,
loop_lower, loop_upper,
lower, upper, inc, chunk, stride);
break;
}
default: {
__pmp_fatal("unknown static scheduling type %d\n", sched);
stride = 0;
lower = loop_lower;
upper = loop_upper;
}
}
*lowerp = lower;
*upperp = upper;
*stridep = stride;
}
__pmp_scheduler_sample(sched);
}
void __ompc_get_thdprv (void ***thdprv, int64_t size,
void *data, int global_id)
{
__pmp_debug(PMP_DEBUG_CALLS, "__ompc_get_thdprv: thdprv=%p, size=%ld, "
"data=%p, global_id=%d\n", thdprv, (long) size, data, global_id);
__pmp_sample(PMP_PROFILE_OMPC_GET_THDPRV);
if (__pmp_get_param()->disabled) {
void **t = (void **) calloc (1, sizeof(void *));
if (t == NULL) {
__pmp_fatal("failed to allocate thread private data\n");
}
t[0] = data;
*thdprv = t;
}
else {
void **t = *thdprv;
if (t == NULL) {
/* TODO: can I reduce the size of this array? Note that it is indexed
* by global_id and global_id's can be arbitrarily assigned to threads
* in general, so this may be difficult. */
void *t_new;
void *t_cur;
t = (void **) calloc(PMP_MAX_THREADS, sizeof(void *));
if (t == NULL) {
__pmp_fatal("failed to allocate thread private data\n");
}
t_new = (void *) t;
t_cur = __pmp_atomic_cmpxchgptr((volatile voidptr_t *) thdprv,
NULL, t_new);
if (t_cur != NULL) {
/* This thread lost the race and another thread has already
* installed a thdprv array. Simply back out this allocation
* and use *thdprv. */
free(t);
t = (void **) t_cur;
}
}
if (t[global_id] == NULL) {
/* The OpenMP 2.5 standard says:
*
* "Each copy of a threadprivate object is initialized once, in the manner
* specified by the program, but at an unspecified point in the program
* prior to the first reference to that copy."
*
* Since the initial values live in the statically allocated block of
* memory passed to our "data" argument, the master thread needs to use
* a dynamically allocated block, just as the additional threads do, so
* that it if it changes its copies of the variables before the program
* enters the first parallel region, those changes have no effect on the
* copies in the additional threads. Observation shows that the code
* generator calls __ompc_get_thdprv from the serial portion of the
* program, for the master thread, before it changes any values.
*
* Note the copying is done without synchronization, which is safe only
* because we're copying statically initialized and subsequently
* unchanged values: copying from the main thread would require a
* barrier.
*/
t[global_id] = (void *) malloc(size);
if (t[global_id] == NULL) {
__pmp_fatal("failed to allocate thread private data");
}
memcpy(t[global_id], data, size);
}
}
}
void __pmp_thread_create (pmp_thread_t *thread)
{
pmp_thread_t *creator = __pmp_get_current_thread();
pthread_t pthread_id;
int result;
pmp_param_t *param = __pmp_get_param();
thread->creator = creator;
if (param->thread_guard_size > 0) {
void *guard;
/* NOTE: this lock is to give a better chance of the guard page
* allocation to immediately follow the pthread stack allocation. */
__pmp_lock(thread->global_id, &__pmp_manager.pthread_create_lock);
/* NOTE: it seems that mmap tends to allocate in an upwards direction
so allocate the guard page first. */
guard = mmap(0, param->thread_guard_size, PROT_NONE,
#if defined(BUILD_OS_DARWIN)
MAP_PRIVATE | MAP_ANON,
#else /* defined(BUILD_OS_DARWIN) */
MAP_PRIVATE | MAP_ANONYMOUS,
#endif /* defined(BUILD_OS_DARWIN) */
0, 0);
if (guard == MAP_FAILED) {
__pmp_warning("unable to allocate a guard page of %ld bytes\n",
(long) param->thread_guard_size);
}
else {
__pmp_debug(PMP_DEBUG_THREAD, "guard page allocated at address %p\n",
guard);
thread->guard_page = guard;
}
}
if ((result = pthread_create(&pthread_id, &__pmp_manager.pthread_attr,
__pmp_thread_run, thread)) != 0) {
if (__pmp_manager.allocated_threads > param->initial_team_size) {
__pmp_warning(
"pthread_create failed when trying to allocate thread %d\n",
__pmp_manager.allocated_threads);
__pmp_warning(
"note this is more than the initial number of threads (%d)\n",
param->initial_team_size);
#if defined(BUILD_OS_DARWIN)
if (sizeof(long) == 4)
#else /* defined(BUILD_OS_DARWIN) */
if (__WORDSIZE == 32)
#endif /* defined(BUILD_OS_DARWIN) */
{
int64_t total_stack = ((int64_t) param->thread_stack_size) *
((int64_t) __pmp_manager.allocated_threads);
if (total_stack > 0x40000000LL) {
__pmp_warning(
"the failure may be due to excessive thread stack size\n");
__pmp_warning(
"try using a smaller setting for PSC_OMP_STACK_SIZE\n");
}
}
}
__pmp_fatal("unable to create thread (result code %d)\n", result);
}
if (param->thread_guard_size > 0) {
__pmp_unlock(thread->global_id, &__pmp_manager.pthread_create_lock);
}
__pmp_atomic_xadd32(&__pmp_manager.waiting_threads, 1);
__pmp_debug(PMP_DEBUG_THREAD, "created thread global_id %d\n",
thread->global_id);
}
static void *__pmp_thread_run (void *arg)
{
pmp_thread_t *thread = (pmp_thread_t *) arg;
pmp_team_t *team;
thread->pthread_id = pthread_self();
#ifdef PMP_NO_NPTL
thread->tid = getpid();
#else
thread->tid = gettid();
#endif
#ifndef PMP_NO_TLS
#ifdef PMP_TLS_THREAD
__pmp_tls_current_thread = thread;
#endif
#ifdef PMP_TLS_LOCAL_ID
__pmp_tls_current_local_id = thread->local_id;
#endif
#ifdef PMP_TLS_GLOBAL_ID
__pmp_tls_current_global_id = thread->global_id;
#endif
#endif
#ifdef PMP_USE_PTHREAD_SIGNALS
if (pthread_sigmask(SIG_BLOCK, &__pmp_manager.mask_block_sigpmp,
NULL) != 0) {
__pmp_fatal("unable to set thread-specific sigmask\n");
}
#else
if (sigprocmask(SIG_BLOCK, &__pmp_manager.mask_block_sigpmp, NULL) != 0) {
__pmp_fatal("unable to set thread-specific sigmask\n");
}
#endif
if (pthread_setspecific(__pmp_manager.thread_key, (void *) thread) != 0) {
__pmp_fatal("unable to set thread-specific data\n");
}
__pmp_debug(PMP_DEBUG_THREAD, "thread global_id %d is running\n",
thread->global_id);
/* Note that there is no synchronization between the creating thread and
* the created thread until here. This is the point where the created
* thread is assigned to do some work. The reason that this is sufficient
* is because the __pmp_thread_wait/wake mechanism is "protected" by
* the thread->sync value which has been pre-initialized. If the creator
* gets to the wake first, then it will just swap in PMP_THREAD_UNBLOCKED
* and its work is done. If it gets to the wake second, then the created
* thread must have got there first and this guarantees that the other
* thread fields will already be initialized by the created thread.
*
* With nested forking, there is the possibility that the creator thread
* will be usurped by another forking thread (there is no lock between
* creation of a thread and that thread being assigned to do work). This
* works for the same reason as described above.
*/
__pmp_thread_wait(thread); /* wait for first assignment */
#ifdef PMP_NO_NPTL
__pmp_shared_catch_segv(thread); /* set up shared segv handler */
#else
__pmp_catch_segv(); /* set up thread's segv handler */
#endif
__pmp_thread_bind(thread); /* bind to the assigned local_id */
while (1) {
__pmp_debug(PMP_DEBUG_THREAD,
"__pmp_thread_run: thread tid=%d, pthread_id=0x%08x "
"global_id=%d, local_id=%d\n",
(int) thread->tid, (int) thread->pthread_id,
(int) thread->global_id, (int) thread->local_id);
team = thread->team;
assert(team != NULL);
#ifndef PMP_NO_TLS
#ifdef PMP_TLS_LOCAL_ID
__pmp_tls_current_local_id = thread->local_id;
#endif
#ifdef PMP_TLS_TEAM
__pmp_tls_current_team = team;
#endif
#endif
__pmp_memory_fence();
__pmp_thread_work(thread); /* do the work */
__pmp_thread_worker_join(team); /* wake up team master */
__pmp_memory_fence();
__pmp_thread_idle(thread); /* thread is now idle */
__pmp_thread_wait(thread); /* wait for more work */
__pmp_thread_bind(thread); /* update binding */
}
/* Currently unreachable */
__pmp_debug(PMP_DEBUG_THREAD, "thread global_id %d is exiting\n",
thread->global_id);
return NULL;
}