Skip to contentSkip to conversation

android: binder: Remove deprecated create_singlethread_workqueue

PATCH In review Bhaktipriya Shridhar 2 participants 2 messages Aug 13, 2016 – Aug 15, 2016 Android drivers

lore
Share & tools
lore

Bhaktipriya Shridhar

author
#0 lore raw

PATCH 1/1 android: binder: Remove deprecated create_singlethread_workqueue

The workqueue is being used to run deferred work for the android binder.

The "binder_deferred_workqueue" queues only a single work item and hence does not require ordering. Also, this workqueue is not being used on a memory recliam path. Hence, the singlethreaded workqueue has been replaced with the use of system_wq.

System workqueues have been able to handle high level of concurrency for a long time now and hence it's not required to have a singlethreaded workqueue just to gain concurrency. Unlike a dedicated per-cpu workqueue created with create_singlethread_workqueue(), system_wq allows multiple work items to overlap executions even on the same CPU; however, a per-cpu workqueue doesn't have any CPU locality or global ordering guarantee unless the target CPU is explicitly specified and thus the increase of local concurrency shouldn't make any difference.

Signed-off-by Bhaktipriya Shridhar <[email protected]>
---
 drivers/android/binder.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)
drivers/android/binder.c +1 -6
index 16288e7..562af94 100644
@@ -59,7 +59,6 @@ static struct dentry *binder_debugfs_dir_entry_proc;
 static struct binder_node *binder_context_mgr_node;
 static kuid_t binder_context_mgr_uid = INVALID_UID;
 static int binder_last_id;
-static struct workqueue_struct *binder_deferred_workqueue;
 
 #define BINDER_DEBUG_ENTRY(name) \
 static int binder_##name##_open(struct inode *inode, struct file *file) \

@@ -3227,7 +3226,7 @@ binder_defer_work(struct binder_proc *proc, enum binder_deferred_state defer)
 	if (hlist_unhashed(&proc->deferred_work_node)) {
 		hlist_add_head(&proc->deferred_work_node,
 				&binder_deferred_list);
-		queue_work(binder_deferred_workqueue, &binder_deferred_work);
+		schedule_work(&binder_deferred_work);
 	}
 	mutex_unlock(&binder_deferred_lock);
 }

@@ -3679,10 +3678,6 @@ static int __init binder_init(void)
 {
 	int ret;
 
-	binder_deferred_workqueue = create_singlethread_workqueue("binder");
-	if (!binder_deferred_workqueue)
-		return -ENOMEM;
-
 	binder_debugfs_dir_entry_root = debugfs_create_dir("binder", NULL);
 	if (binder_debugfs_dir_entry_root)
 		binder_debugfs_dir_entry_proc = debugfs_create_dir("proc",

--
2.1.4

Acked-by on v1 1/1
#1 lore raw
Quoted 16 lines · Bhaktipriya Shridhar

The workqueue is being used to run deferred work for the android binder.

The "binder_deferred_workqueue" queues only a single work item and hence does not require ordering. Also, this workqueue is not being used on a memory recliam path. Hence, the singlethreaded workqueue has been replaced with the use of system_wq.

System workqueues have been able to handle high level of concurrency for a long time now and hence it's not required to have a singlethreaded workqueue just to gain concurrency. Unlike a dedicated per-cpu workqueue created with create_singlethread_workqueue(), system_wq allows multiple work items to overlap executions even on the same CPU; however, a per-cpu workqueue doesn't have any CPU locality or global ordering guarantee unless the target CPU is explicitly specified and thus the increase of local concurrency shouldn't make any difference.

Quoted 1 line
Signed-off-by Bhaktipriya Shridhar <[email protected]>
Acked-by Tejun Heo <[email protected]>

Thanks.

Signature · 1 line
tejun