Paris7/work-stealing-scheduler
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modifications

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* move some .h code in .c
* remove unnecessary typedef
* use number of sleeping threads instead of global exit variable
* add some error verification
* use qlen variable

it currently works but probably janky as hell
This commit is contained in:
Mylloon 2024-04-19 16:06:56 +02:00
parent 6b891cf338
commit e97e332c3f
Signed by: Anri
GPG key ID: A82D63DFF8D1317F
2 changed files with 103 additions and 82 deletions
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24
includes/sched.h
View file

@ -3,34 +3,10 @@
#include <pthread.h>
#include <unistd.h>
#define MAX_TASKS 81920
struct scheduler;
typedef void (*taskfunc)(void *, struct scheduler *);
typedef struct task_info {
taskfunc f;
void *closure;
} taskinfo;
struct scheduler {
/* Mutex qui protège la structure */
pthread_mutex_t mutex;
/* Indicateur de changement d'état */
pthread_cond_t cond;
/* Position actuelle dans la pile */
int top;
/* Tâches */
taskinfo tasks[MAX_TASKS];
/* Si tout est terminé */
int exit;
};
static inline int
sched_default_threads(void)
{

161
src/sched.c
View file

@ -2,71 +2,55 @@
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
struct task_info {
void *closure;
taskfunc f;
};
struct scheduler {
/* Indicateur de changement d'état */
pthread_cond_t cond;
/* Taille de la pile */
int qlen;
/* Mutex qui protège la structure */
pthread_mutex_t mutex;
/* Nombre de threads en attente */
int nthsleep;
/* Pile de tâches */
struct task_info *tasks;
/* Position actuelle dans la pile */
int top;
};
/* Ordonnanceur partagé */
static struct scheduler sched;
/* Lance une tâche de la pile */
void *
worker_routine(void *arg)
{
struct scheduler *s = (struct scheduler *)arg;
while(1) {
pthread_mutex_lock(&s->mutex);
if(s->exit == 1) {
pthread_mutex_unlock(&s->mutex);
printf("finalement..rien a faire, ciao\n");
break;
}
// S'il on a rien à faire
if(s->top == -1) {
// printf("attend..\n");
pthread_cond_wait(&s->cond, &s->mutex);
pthread_mutex_unlock(&s->mutex);
// printf("reveillé!\n");
continue;
}
// printf("lancement tâche #%d\n", s->top);
// Extrait la tâche de la pile
taskfunc f = s->tasks[s->top].f;
void *closure = s->tasks[s->top].closure;
s->top--;
pthread_mutex_unlock(&s->mutex);
// Exécute la tâche
f(closure, s);
// Signale s'il n'y a plus rien à faire
if(s->top == -1) {
printf("va falloir partir\n");
pthread_mutex_lock(&s->mutex);
s->exit = 1;
pthread_cond_broadcast(&s->cond);
pthread_mutex_unlock(&s->mutex);
}
}
return NULL;
}
void *worker_routine(void *);
int
sched_init(int nthreads, int qlen, taskfunc f, void *closure)
{
if(nthreads == 0) {
if(qlen <= 0) {
fprintf(stderr, "qlen must be greater than 0\n");
return -1;
}
sched.qlen = qlen;
if(nthreads < 0) {
fprintf(stderr, "nthreads must be greater than 0\n");
return -1;
} else if(nthreads == 0) {
nthreads = sched_default_threads();
}
// TODO : Actuellement on n'utilises pas qlen
// => On utilise une pile de taille fixe
(void)qlen;
sched.top = -1;
sched.exit = 0;
if(pthread_mutex_init(&sched.mutex, NULL) != 0) {
fprintf(stderr, "Can't init mutex\n");
return -1;
@ -77,15 +61,34 @@ sched_init(int nthreads, int qlen, taskfunc f, void *closure)
return -1;
}
sched.top = -1;
if((sched.tasks = malloc(qlen * sizeof(struct task_info))) == NULL) {
fprintf(stderr, "Can't allocate memory for stack\n");
return -1;
}
pthread_t threads[nthreads];
for(int i = 0; i < nthreads; ++i) {
if(pthread_create(&threads[i], NULL, worker_routine, &sched) != 0) {
fprintf(stderr, "Can't create threads\n");
fprintf(stderr, "Can't create the thread %d", i);
if(i > 0) {
fprintf(stderr, ", cancelling already created threads...\n");
for(int j = 0; j < i; ++j) {
if(pthread_cancel(threads[j]) != 0) {
fprintf(stderr, "Can't cancel the thread %d\n", j);
}
}
} else {
fprintf(stderr, "\n");
}
free(sched.tasks);
return -1;
}
}
if(sched_spawn(f, closure, &sched) != 0) {
if(sched_spawn(f, closure, &sched) < 0) {
fprintf(stderr, "Can't create the initial task\n");
return -1;
}
@ -105,17 +108,59 @@ sched_spawn(taskfunc f, void *closure, struct scheduler *s)
{
pthread_mutex_lock(&s->mutex);
if(s->top + 1 >= MAX_TASKS) {
if(s->top + 1 >= s->qlen) {
pthread_mutex_unlock(&s->mutex);
errno = EAGAIN;
fprintf(stderr, "Stack is full\n");
return -1;
}
s->tasks[++s->top] = (taskinfo){f, closure};
s->tasks[++s->top] = (struct task_info){closure, f};
pthread_cond_signal(&s->cond);
pthread_mutex_unlock(&s->mutex);
return 0;
}
void *
worker_routine(void *arg)
{
struct scheduler *s = (struct scheduler *)arg;
while(1) {
pthread_mutex_lock(&s->mutex);
// S'il on a rien à faire
if(s->top == -1) {
// tentative avec nthsleep???? pourquoi 10 aaaaa j'ai 12 coeurs??
s->nthsleep++;
if(s->nthsleep >= 10) {
pthread_mutex_unlock(&s->mutex);
break;
}
pthread_cond_wait(&s->cond, &s->mutex);
pthread_mutex_unlock(&s->mutex);
continue;
}
// Extrait la tâche de la pile
taskfunc f = s->tasks[s->top].f;
void *closure = s->tasks[s->top].closure;
s->top--;
pthread_mutex_unlock(&s->mutex);
// Exécute la tâche
f(closure, s);
// Signale s'il n'y a plus rien à faire
if(s->top == -1) {
pthread_mutex_lock(&s->mutex);
pthread_cond_broadcast(&s->cond);
pthread_mutex_unlock(&s->mutex);
}
}
return NULL;
}