Paris7/work-stealing-scheduler
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This commit is contained in:
Mylloon 2024-04-22 02:09:51 +02:00
parent 7a4960412b
commit 222e9cb303
Signed by: Anri
GPG key ID: A82D63DFF8D1317F
1 changed files with 103 additions and 127 deletions
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220
src/sched.c
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@ -11,17 +11,15 @@ struct task_info {
taskfunc f;
};
struct robber {
pthread_cond_t cond;
pthread_mutex_t mutex;
};
struct scheduler {
/* Taille des piles */
int qlen;
/* Variable de conditions pour reveillé les threads au besoin */
pthread_cond_t cond;
/* Mutex qui protège les piles */
pthread_mutex_t *mutex;
pthread_mutex_t mutex;
/* Nombre de threads instanciés */
int nthreads;
@ -32,11 +30,13 @@ struct scheduler {
/* Liste des threads */
pthread_t *threads;
/* Positions actuelle dans la pile */
int *top;
/* Compteur des threads dormants */
int nthsleep;
/* Infos pour le vol */
struct robber rob;
/* Stack sous forme de dequeu pour gérer la récupération
* du premier élément ajouté */
int *top;
int *bottom;
};
/* Ordonnanceur partagé */
@ -48,25 +48,22 @@ void *sched_worker(void *);
/* Nettoie les opérations effectuées par l'initialisation de l'ordonnanceur */
int sched_init_cleanup(int);
/* sched_spawn sur un thread spécifique */
int sched_spawn_core(taskfunc, void *, struct scheduler *, int);
/* Récupère l'index du thread courant */
int current_thread(struct scheduler *);
int
sched_init(int nthreads, int qlen, taskfunc f, void *closure)
{
sched.mutex = NULL;
sched.tasks = NULL;
sched.threads = NULL;
sched.top = NULL;
sched.bottom = NULL;
if(qlen <= 0) {
fprintf(stderr, "qlen must be greater than 0\n");
return -1;
}
sched.qlen = qlen;
sched.qlen = qlen + 1; // circular buffer
if(nthreads < 0) {
fprintf(stderr, "nthreads must be greater than 0\n");
@ -76,29 +73,32 @@ sched_init(int nthreads, int qlen, taskfunc f, void *closure)
}
sched.nthreads = nthreads;
// Initialisation des infos de vol
sched.rob =
(struct robber){PTHREAD_COND_INITIALIZER, PTHREAD_MUTEX_INITIALIZER};
sched.nthsleep = 0;
// Initialisation des mutex de chaque processus
if(!(sched.mutex = malloc(sched.nthreads * sizeof(pthread_mutex_t)))) {
perror("Mutexes");
// Initialisation du mutex
if(pthread_mutex_init(&sched.mutex, NULL) != 0) {
fprintf(stderr, "Can't init mutex\n");
return sched_init_cleanup(-1);
}
for(int i = 0; i < sched.nthreads; ++i) {
if(pthread_mutex_init(&sched.mutex[i], NULL) != 0) {
fprintf(stderr, "Can't init mutex for thread %d\n", i);
// Initialisation variable de condition
if(pthread_cond_init(&sched.cond, NULL) != 0) {
fprintf(stderr, "Can't init varcond\n");
return sched_init_cleanup(-1);
}
}
// Initialisation du curseur suivant l'état de la pile de chaque processus
if(!(sched.top = malloc(sched.nthreads * sizeof(int)))) {
perror("Cursor top stack\n");
perror("Cursor top stack");
return sched_init_cleanup(-1);
}
if(!(sched.bottom = malloc(sched.nthreads * sizeof(int)))) {
perror("Cursor bottom stack");
return sched_init_cleanup(-1);
}
for(int i = 0; i < sched.nthreads; ++i) {
sched.top[i] = -1;
sched.top[i] = 0;
sched.bottom[i] = 0;
}
// Allocation mémoire pour la pile de chaque processus
@ -113,17 +113,22 @@ sched_init(int nthreads, int qlen, taskfunc f, void *closure)
}
}
// Ajoute la tâche initiale
if(sched_spawn_core(f, closure, &sched, 0) < 0) {
fprintf(stderr, "Can't create the initial task\n");
return sched_init_cleanup(-1);
}
// Créer les threads
if(!(sched.threads = malloc(sched.nthreads * sizeof(pthread_t *)))) {
perror("Threads");
return sched_init_cleanup(-1);
}
// Ajoute la tâche initiale
if(sched_spawn(f, closure, &sched) < 0) {
fprintf(stderr, "Can't create the initial task\n");
return sched_init_cleanup(-1);
}
// Initialise l'aléatoire
srand(time(NULL));
// Démarre les threads
for(int i = 0; i < nthreads; ++i) {
if(pthread_create(&sched.threads[i], NULL, sched_worker, &sched) != 0) {
fprintf(stderr, "Can't create the thread %d\n", i);
@ -156,14 +161,9 @@ sched_init(int nthreads, int qlen, taskfunc f, void *closure)
int
sched_init_cleanup(int ret_code)
{
if(sched.mutex) {
for(int i = 0; i < sched.nthreads; ++i) {
pthread_mutex_destroy(&sched.mutex[i]);
}
pthread_mutex_destroy(&sched.mutex);
free(sched.mutex);
sched.mutex = NULL;
}
pthread_cond_destroy(&sched.cond);
if(sched.tasks) {
for(int i = 0; i < sched.nthreads; ++i) {
@ -187,23 +187,12 @@ sched_init_cleanup(int ret_code)
sched.top = NULL;
}
pthread_cond_destroy(&sched.rob.cond);
pthread_mutex_destroy(&sched.rob.mutex);
return ret_code;
}
int
sched_spawn(taskfunc f, void *closure, struct scheduler *s)
{
int core;
if((core = current_thread(s)) < 0) {
fprintf(stderr, "Thread not in list, who am I?\n");
return -1;
if(sched.bottom) {
free(sched.bottom);
sched.bottom = NULL;
}
// On ajoute la tâche sur la pile du thread courant
return sched_spawn_core(f, closure, s, core);
return ret_code;
}
int
@ -220,21 +209,27 @@ current_thread(struct scheduler *s)
}
int
sched_spawn_core(taskfunc f, void *closure, struct scheduler *s, int core)
sched_spawn(taskfunc f, void *closure, struct scheduler *s)
{
pthread_mutex_lock(&s->mutex[core]);
int th;
if((th = current_thread(s)) < 0) {
th = 0;
}
if(s->top[core] + 1 >= s->qlen) {
pthread_mutex_unlock(&s->mutex[core]);
errno = EAGAIN;
pthread_mutex_lock(&s->mutex);
int next = (s->top[th] + 1) % s->qlen;
if(next == s->bottom[th]) {
pthread_mutex_unlock(&s->mutex);
fprintf(stderr, "Stack is full\n");
errno = EAGAIN;
return -1;
}
s->top[core]++;
s->tasks[core][s->top[core]] = (struct task_info){closure, f};
s->tasks[th][s->top[th]] = (struct task_info){closure, f};
s->top[th] = next;
pthread_mutex_unlock(&s->mutex[core]);
pthread_mutex_unlock(&s->mutex);
return 0;
}
@ -247,78 +242,59 @@ sched_worker(void *arg)
// Récupère le processus courant (index tableau)
int curr_th;
if((curr_th = current_thread(s)) < 0) {
fprintf(stderr, "Worker thread not tracked, exiting...\n");
fprintf(stderr, "Thread unknown, exiting...\n");
return NULL;
}
struct task_info task;
int found;
while(1) {
pthread_mutex_lock(&s->rob.mutex);
pthread_mutex_lock(&s->mutex[curr_th]);
found = 0;
pthread_mutex_lock(&s->mutex);
// Si rien à faire
if(s->top[curr_th] == -1) {
// Cherche un thread (avec le + de tâches en attente) à voler
int stolen = -1;
pthread_cond_wait(&s->rob.cond, &s->rob.mutex);
for(int i = 0, max_tasks = -1; i < s->nthreads; ++i) {
if(i == curr_th) {
continue; // On ne se vole pas soi-même
if(s->bottom[curr_th] != s->top[curr_th]) {
found = 1;
s->top[curr_th] = (s->top[curr_th] - 1 + s->qlen) % s->qlen;
task = s->tasks[curr_th][s->top[curr_th]];
}
// Verrouille le mutex du thread candidat
/* pthread_mutex_lock(&s->mutex[i]); */
if(!found) {
// Vol car aucune tâche trouvée
for(int i = 0, k = rand() % (s->nthreads + 1), target;
i < s->nthreads; ++i) {
target = (i + curr_th) % s->nthreads;
if(s->top[i] > max_tasks) {
max_tasks = s->top[i];
stolen = i;
}
// Déverrouille le mutex du thread candidat
/* pthread_mutex_unlock(&s->mutex[i]); */
}
// Vole une tâche à un autre thread
if(stolen >= 0) {
struct task_info theft;
pthread_mutex_lock(&s->mutex[stolen]);
// Actuellement on prend la tâche la plus ancienne en
// inversant la première et la dernière
// TODO: Récupérer la premiere tâche tout en respectant l'ordre
theft = s->tasks[stolen][0];
s->tasks[stolen][0] = s->tasks[stolen][s->top[stolen]];
s->top[stolen]--;
pthread_mutex_unlock(&s->mutex[stolen]);
pthread_mutex_unlock(&s->mutex[curr_th]);
pthread_mutex_unlock(&s->rob.mutex);
// Rajoute la tâche sur notre pile
sched_spawn_core(theft.f, theft.closure, s, curr_th);
continue;
}
pthread_mutex_unlock(&s->mutex[curr_th]);
pthread_cond_broadcast(&s->rob.cond);
pthread_mutex_unlock(&s->rob.mutex);
printf("%d se tire\n", curr_th);
if(s->bottom[target] != s->top[target]) {
// Tâche trouvée
found = 1;
s->top[target] = (s->top[target] - 1 + s->qlen) % s->qlen;
task = s->tasks[target][s->top[target]];
break;
}
}
// Extrait la tâche de la pile
taskfunc f = s->tasks[curr_th][s->top[curr_th]].f;
void *closure = s->tasks[curr_th][s->top[curr_th]].closure;
s->top[curr_th]--;
pthread_mutex_unlock(&s->mutex[curr_th]);
// Aucune tâche à faire
if(!found) {
s->nthsleep++;
// Ne partir que si tout le monde dort
if(s->nthsleep >= s->nthreads) {
pthread_cond_broadcast(&s->cond);
pthread_mutex_unlock(&s->mutex);
break;
}
pthread_cond_wait(&s->cond, &s->mutex);
s->nthsleep--;
pthread_mutex_unlock(&s->mutex);
continue;
}
}
pthread_cond_broadcast(&s->cond);
pthread_mutex_unlock(&s->mutex);
// Exécute la tâche
f(closure, s);
pthread_cond_broadcast(&s->rob.cond);
pthread_mutex_unlock(&s->rob.mutex);
task.f(task.closure, s);
}
return NULL;