#include "nbody.h" // Declarations
#include "../single-thread/nbody.c" // Include all functions from the single threaded version
+#include "graphics.h" // For declaration of Graphics_Run only
+
// --- Variable declarations --- //
pthread_t compute_thread; // The thread responsible for computations; it spawns worker threads
pthread_t * worker_thread = NULL; //Array of worker threads responsible for Force and Position updates
System * sub_system = NULL; //Array of Systems used to divide up the main "universe" System for worker threads
-pthread_mutex_t mutex_workers; // Mutex used for the barrier between Force and Position updates
-pthread_cond_t workers_done_cv; // Conditional used for the barrier between Force and Position updates
-unsigned workers_busy; // Number of workers currently doing something
+System * nested_sub_system = NULL; //Array of Systems for division of "universe" for the nested worker threads
pthread_mutex_t mutex_runstate; // Mutex around the runstate
+pthread_attr_t attr; //thread attribute for the workers.
+
+Barrier force_barrier; // I laughed at this variable name. A bit sad really.
+Barrier position_barrier;
+
+
+Barrier graphics_barrier;
+
+
/**
* @function Compute_Thread
* @purpose Thread - Continuously computes steps for a system of bodies. Seperate from graphics functions.
if (options.num_threads <= 0)
options.num_threads = (DEFAULT_WORKING_THREADS > 1) ? DEFAULT_WORKING_THREADS : 1;
+ if (options.nested_threads <= 0)
+ options.nested_threads = 1;
+
// Do a sanity check; there is no point spawning more threads than bodies.
if (options.num_threads > s->N)
{
options.num_threads = s->N;
}
+ pthread_attr_init(&attr);
+ pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); //Needs to be detached, so that memory can be reused.
+
if (options.num_threads > 1) // Allocate worker threads and sub systems, as long as there would be more than 1
{
- worker_thread = (pthread_t*)(calloc(options.num_threads, sizeof(pthread_t)));
- if (worker_thread == NULL)
- {
- perror("Couldn't allocate array of worker threads");
- QuitProgram(true);
- pthread_exit(NULL);
- }
- sub_system = (System*)(calloc(options.num_threads, sizeof(System)));
- if (sub_system == NULL)
+ worker_thread = Allocate_Threads(options.num_threads);
+ sub_system = Split_System(&universe, options.num_threads);
+
+ if (options.nested_threads > 1)
+ nested_sub_system = Split_System(&universe, options.nested_threads);
+
+ #ifdef PERSISTENT_THREADS
+ for (unsigned i = 0; i < options.num_threads; ++i)
{
- perror("Couldn't allocate array of systems for worker threads to use");
- QuitProgram(true);
- pthread_exit(NULL);
+ if (pthread_create(worker_thread+i, & attr, Worker_Thread, (void*)(sub_system+i)) != 0)
+ {
+ perror("In compute thread, couldn't create worker thread");
+ QuitProgram(true);
+ pthread_exit(NULL);
+ }
}
+ #endif //PERSISTENT_THREADS
- // Divide up the Body array owned by s into options.num_threads arrays, one for each worker thread
- unsigned bodies_per_system = (s->N) / options.num_threads;
- unsigned remainder = (s->N) % options.num_threads;
- for (unsigned i = 0; i < options.num_threads; ++i)
+
+ }
+ #ifdef PERSISTENT_THREADS
+ else
+ {
+ while (!ExitCondition())
{
- sub_system[i].body = (s->body)+(i*bodies_per_system);
- sub_system[i].N = bodies_per_system;
- sub_system[i].steps = 0;
- if (i == options.num_threads - 1)
- sub_system[i].N += remainder; // The last thread gets the remainder
+ if (options.verbosity != 0 && universe.steps % options.verbosity == 1)
+ DisplayStatistics();
+ // Just do everything in this thread
+ System_Forces(s, s);
+ System_Positions(s);
}
+ QuitProgram(false);
+ pthread_exit(NULL);
}
-
- pthread_attr_t attr; //thread attribute for the workers.
- pthread_attr_init(&attr);
- pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); //Needs to be detached, so that memory can be reused.
-
+ #else
// The main computation loop
- while (true)
+ while (!ExitCondition())
{
-
- if (runstate != RUN) pthread_exit(NULL); //Check whether the main thread wants to exit
-
-
-
- //Check whether the program should quit due to steps being computed, or a timeout
- if (options.timeout > 0.0)
- {
- if ((unsigned)(time(NULL) - options.start_time.tv_sec) >= options.timeout)
- QuitProgram(false);
- }
-
- if (options.num_steps > 0 && universe.steps > options.num_steps)
- QuitProgram(false);
-
- if (options.draw_graphics == false && options.verbosity != 0
- && universe.steps % options.verbosity == 1)
- {
+ if (options.verbosity != 0 && universe.steps % options.verbosity == 1)
DisplayStatistics();
- }
-
if (options.num_threads <= 1)
{
-
- workers_busy = options.num_threads; //All threads working
-
//Compute forces
for (unsigned i = 0; i < options.num_threads; ++i)
{
QuitProgram(true);
pthread_exit(NULL);
}
+
}
-
- //Barrier - Wait for forces to be computed
- pthread_mutex_lock(&mutex_workers);
- while (workers_busy > 0)
- pthread_cond_wait(&workers_done_cv, &mutex_workers);
- pthread_mutex_unlock(&mutex_workers);
+ Barrier_Wait(&force_barrier);
//All the forces are now computed
-
- workers_busy = options.num_threads; //All threads working
+
+ if (options.draw_graphics && options.pedantic_graphics)
+ {
+ Barrier_Wait(&graphics_barrier);
+ }
//Compute positions
for (unsigned i = 0; i < options.num_threads; ++i)
}
//Wait for positions to be computed
- pthread_mutex_lock(&mutex_workers);
- while (workers_busy > 0)
- pthread_cond_wait(&workers_done_cv, &mutex_workers);
- pthread_mutex_unlock(&mutex_workers);
+ Barrier_Wait(&position_barrier);
+
//Update number of steps computed
universe.steps += 1;
+
+
+
}
+ QuitProgram(false);
+ #endif //PERSISTENT_THREADS
+ return NULL;
}
+/**
+ * @function BeforeDraw
+ * @purpose Called in graphics thread before the draw loop
+ * When --pedantic-graphics enabled, will wait for position computations to finish before drawing
+ * Otherwise does nothing
+ */
+void BeforeDraw()
+{
+ if (options.verbosity != 0 && universe.steps % options.verbosity == 0)
+ DisplayStatistics();
+ //printf("BEFORE DRAW\n");
+ if (!options.pedantic_graphics)
+ return;
+
+ Barrier_Wait(&position_barrier);
+
+
+ Barrier_Enter(&graphics_barrier);
+}
+
+/**
+ * @function AfterDraw
+ * @purpose Called in graphics thread after the draw loop
+ * When --pedantic-graphics is supplied, will signal computation thread that drawing is finished
+ * So that positions can be safely altered
+ * Otherwise does nothing
+ */
+void AfterDraw()
+{
+ universe.steps += 1;
+ if (!options.pedantic_graphics)
+ return;
+ Barrier_Leave(&graphics_barrier);
+
+}
+
+#ifdef PERSISTENT_THREADS
+
+/**
+ * @function Worker_Thread
+ * @purpose Thread - Calculate stuff
+ */
+void * Worker_Thread(void * arg)
+{
+ System * s = (System*)(arg);
+
+
+ pthread_t * nested_workers = NULL;
+ System_ForcePair * system_pairs = NULL;
+ System * nested_position = NULL;
+
+ Barrier nested_barrier;
+ Barrier_Init(&nested_barrier);
+
+ printf("options.nested_threads == %d\n", (int)(options.nested_threads));
+
+ if (options.nested_threads != 1)
+ {
+
+ system_pairs = (System_ForcePair*)(calloc(options.nested_threads, sizeof(System_ForcePair)));
+ if (system_pairs == NULL) // Handle tedious error cases
+ {
+ perror("Couldn't allocate array of system pairs");
+ QuitProgram(true);
+ pthread_exit(NULL);
+ }
+ nested_workers = Allocate_Threads(options.nested_threads);
+ nested_position =
+
+ for (unsigned i = 0; i < options.nested_threads; ++i)
+ {
+ system_pairs[i].A = s;
+ system_pairs[i].B = nested_sub_system+i;
+ }
+ }
+
+ while (!ExitCondition())
+ {
+
+ if (options.nested_threads == 1)
+ {
+ Barrier_Enter(&force_barrier);
+ System_Forces(s, &universe);
+ Barrier_Leave(&force_barrier);
+ }
+ else
+ {
+ for (unsigned i = 0; i < options.nested_threads; ++i)
+ {
+ if (pthread_create(nested_workers+i, &attr, Force_Thread, (void*)(system_pairs+i)) != 0)
+ {
+ perror("In worker thread, couldn't create nested worker thread (force)");
+ QuitProgram(true);
+ free(nested_workers);
+ pthread_exit(NULL);
+ }
+ }
+ }
+ //printf("Computed forces for %p\n", arg);
+ Barrier_Wait(&force_barrier);
+ //printf("Computed ALL forces\n");
+
+ if (options.draw_graphics && options.pedantic_graphics)
+ Barrier_Wait(&graphics_barrier);
+
+ Barrier_Enter(&position_barrier);
+
+ System_Positions(s);
+
+ Barrier_Leave(&position_barrier);
+ //printf("Computed positions for %p\n", arg);
+ Barrier_Wait(&position_barrier);
+ //printf("Computed ALL positions\n");
+ }
+ printf("Worker thread exits\n");
+ QuitProgram(false);
+ pthread_exit(NULL);
+}
+
+#endif //PERSISTENT_THREADS
+
/**
* @function Force_Thread
* @purpose Thread - Calculates the forces on objects in a System
*/
void * Force_Thread(void * s)
{
-
- System_Forces((System*)s, &universe); //Simple wrapper
+ System_ForcePair * pair = (System_ForcePair*)s;
+ Barrier_Enter(&force_barrier);
+
+ System_Forces(pair->A, pair->B); //Simple wrapper
+
+ Barrier_Leave(&force_barrier);
- pthread_mutex_lock(&mutex_workers);
- workers_busy -= 1; // Count this thread as done
- if (workers_busy == 0)
- {
- pthread_cond_signal(&workers_done_cv); // All threads done; wake up the compute_thread
- }
- pthread_mutex_unlock(&mutex_workers);
return NULL;
}
+
/**
* @function Position_Thread
* @purpose Thread - Calculates the positions of objects in a System
*/
void * Position_Thread(void * s)
{
-
+ Barrier_Enter(&position_barrier);
System_Positions((System*)s); // Simple wrapper
-
- pthread_mutex_lock(&mutex_workers);
- workers_busy -= 1; // Count this thread as done
- if (workers_busy == 0)
- {
- pthread_cond_signal(&workers_done_cv); //All threads done; wake up the compute_thread
- }
- pthread_mutex_unlock(&mutex_workers);
+ Barrier_Leave(&position_barrier);
return NULL;
}
*/
void QuitProgram(bool error)
{
-
+ if (runstate == QUIT || runstate == QUIT_ERROR)
+ return; //Don't do anything if already quitting
pthread_mutex_lock(&mutex_runstate); // aquire mutex
if (error) // set the runstate
runstate = QUIT_ERROR;
* @function Simulation_Run
* @purpose Initialise and start the simulation. Will be called in the main thread.
* Replaces the single-threaded macro that does nothing, and sets up the compute thread
+ * @param argc - Number of arguments - Passed to Graphics_Run if needed
+ * @param argv - Argument strings - Passed to Graphics_Run if needed
*/
-void Simulation_Run()
+void Simulation_Run(int argc, char ** argv)
{
atexit(Thread_Cleanup);
- if (options.draw_graphics == false)
+ Barrier_Init(&force_barrier);
+ Barrier_Init(&position_barrier);
+ Barrier_Init(&graphics_barrier);
+
+
+ if (options.draw_graphics)
{
+ // The graphics are enabled, so create a thread to do computations
+ // Graphics are done in the main loop
+ //printf("Graphics are enabled\n");
+ #ifdef PERSISTENT_THREADS
Compute_Thread((void*)(&universe));
+ #else
+ if (pthread_create(&compute_thread, NULL, Compute_Thread, (void*)&universe) != 0)
+ {
+ perror("Error creating compute thread");
+ exit(EXIT_FAILURE);
+ }
+ #endif //PERSISTENT_THREADS
+ //printf("Run compute thread\n");
+ Graphics_Run(argc, argv);
+ }
+ else
+
+ Compute_Thread((void*)(&universe)); // Graphics are disabled, so do computations in the main thread
+}
- // If there are no graphics, run the computation loop in the main thread
- // The call to pthread_exit(NULL) in the computation loop ends the main thread
- // This means the main function never calls the Graphics_Run function
- // Without this condition here, Graphics_Display would essentially be running a busy loop in the main thread
-
- fprintf(stderr,"Should not see this\n");
- exit(EXIT_FAILURE);
+
+void Barrier_Init(Barrier * b)
+{
+ b->threads_busy = 0;
+}
+
+void Barrier_Enter(Barrier * b)
+{
+ pthread_mutex_lock(&(b->mutex));
+ b->threads_busy += 1;
+ pthread_mutex_unlock(&(b->mutex));
+}
+
+void Barrier_Leave(Barrier * b)
+{
+ pthread_mutex_lock(&(b->mutex));
+ b->threads_busy -= 1;
+ if (b->threads_busy == 0)
+ {
+ pthread_cond_signal(&(b->threads_done_cv));
}
-
- // Create a thread to handle computation loop
- if (pthread_create(&compute_thread, NULL, Compute_Thread, (void*)&universe) != 0)
+ pthread_mutex_unlock(&(b->mutex));
+}
+
+void Barrier_Wait(Barrier * b)
+{
+ pthread_mutex_lock(&(b->mutex));
+ while (b->threads_busy > 0)
+ pthread_cond_wait(&(b->threads_done_cv), &(b->mutex));
+ pthread_mutex_unlock(&(b->mutex));
+}
+
+/**
+ * @function Split_System
+ * @purpose Helper to divide one system into an array of systems
+ * Each sub system will have N = (s->N / n) bodies in it
+ * @param s - The original system (typically &universe)
+ * @param n - The number of sub systems in the array
+ *
+ * WARNING: It is the caller's responsibility to free() the returned array
+ */
+System * Split_System(System * s, unsigned n)
+{
+ System * result = (System*)(calloc(n, sizeof(System)));
+ if (result == NULL)
+ {
+ perror("Couldn't create array of sub systems");
+ QuitProgram(true);
+ pthread_exit(NULL);
+ }
+
+ unsigned n_per_system = (s->N) / n;
+ unsigned remainder = (s->N) % n;
+
+ for (unsigned i = 0; i < n; ++i)
+ {
+ result[i].N = n_per_system;
+ if (i == n-1)
+ result[i].N += remainder;
+ result[i].body = (s->body) + (n_per_system * i);
+ result[i].steps = 0;
+ }
+ return result;
+}
+
+/**
+ * @function Allocate_Threads
+ * @purpose Helper function to allocate an array of pthread_t objects
+ * Handles all the pointless, er, "important" error checking that should be done
+ * @param n - Number of threads in the array
+ *
+ * WARNING: Remember to free() the array!!!
+ */
+pthread_t * Allocate_Threads(unsigned n)
+{
+ pthread_t * result = (pthread_t*)(calloc(n, sizeof(pthread_t)));
+ if (result == NULL)
{
- perror("Error creating compute thread");
- exit(EXIT_FAILURE);
+ perror("Unable to allocate memory for threads");
+ QuitProgram(true);
+ pthread_exit(NULL);
}
+ return result;
}
git.ucc.asn.au / matches / honours.git / blobdiff
UCC git Repository :: git.ucc.asn.au