diff options
author | Marek Olšák <[email protected]> | 2017-07-10 21:17:04 +0200 |
---|---|---|
committer | Marek Olšák <[email protected]> | 2017-07-17 10:57:20 -0400 |
commit | 59ad7697705a65940f6370c28729aff87d446b46 (patch) | |
tree | 6b66cda9329a9648d5767035aae9c78e52dde02d /src/util | |
parent | 465bb47d6f6c1d41ddb6d99fee31f2df2fbc7b5a (diff) |
util/u_queue: add an option to resize the queue when it's full
Consider the following situation:
mtx_lock(mutex);
do_something();
util_queue_add_job(...);
mtx_unlock(mutex);
If the queue is full, util_queue_add_job will wait for a free slot.
If the job which is currently being executed tries to lock the mutex,
it will be stuck forever, because util_queue_add_job is stuck.
The deadlock can be trivially resolved by increasing the queue size
(reallocating the queue) in util_queue_add_job if the queue is full.
Then util_queue_add_job becomes wait-free.
radeonsi will use it.
Reviewed-by: Nicolai Hähnle <[email protected]>
Diffstat (limited to 'src/util')
-rw-r--r-- | src/util/u_queue.c | 37 | ||||
-rw-r--r-- | src/util/u_queue.h | 2 |
2 files changed, 36 insertions, 3 deletions
diff --git a/src/util/u_queue.c b/src/util/u_queue.c index cb5903014e7..49361c3dadf 100644 --- a/src/util/u_queue.c +++ b/src/util/u_queue.c @@ -204,6 +204,7 @@ util_queue_init(struct util_queue *queue, memset(queue, 0, sizeof(*queue)); queue->name = name; + queue->flags = flags; queue->num_threads = num_threads; queue->max_jobs = max_jobs; @@ -329,9 +330,39 @@ util_queue_add_job(struct util_queue *queue, assert(queue->num_queued >= 0 && queue->num_queued <= queue->max_jobs); - /* if the queue is full, wait until there is space */ - while (queue->num_queued == queue->max_jobs) - cnd_wait(&queue->has_space_cond, &queue->lock); + if (queue->num_queued == queue->max_jobs) { + if (queue->flags & UTIL_QUEUE_INIT_RESIZE_IF_FULL) { + /* If the queue is full, make it larger to avoid waiting for a free + * slot. + */ + unsigned new_max_jobs = queue->max_jobs + 8; + struct util_queue_job *jobs = + (struct util_queue_job*)calloc(new_max_jobs, + sizeof(struct util_queue_job)); + assert(jobs); + + /* Copy all queued jobs into the new list. */ + unsigned num_jobs = 0; + unsigned i = queue->read_idx; + + do { + jobs[num_jobs++] = queue->jobs[i]; + i = (i + 1) % queue->max_jobs; + } while (i != queue->write_idx); + + assert(num_jobs == queue->num_queued); + + free(queue->jobs); + queue->jobs = jobs; + queue->read_idx = 0; + queue->write_idx = num_jobs; + queue->max_jobs = new_max_jobs; + } else { + /* Wait until there is a free slot. */ + while (queue->num_queued == queue->max_jobs) + cnd_wait(&queue->has_space_cond, &queue->lock); + } + } ptr = &queue->jobs[queue->write_idx]; assert(ptr->job == NULL); diff --git a/src/util/u_queue.h b/src/util/u_queue.h index edd6babb5c7..ff713ae54d6 100644 --- a/src/util/u_queue.h +++ b/src/util/u_queue.h @@ -43,6 +43,7 @@ extern "C" { #endif #define UTIL_QUEUE_INIT_USE_MINIMUM_PRIORITY (1 << 0) +#define UTIL_QUEUE_INIT_RESIZE_IF_FULL (1 << 1) /* Job completion fence. * Put this into your job structure. @@ -69,6 +70,7 @@ struct util_queue { cnd_t has_queued_cond; cnd_t has_space_cond; thrd_t *threads; + unsigned flags; int num_queued; unsigned num_threads; int kill_threads; |