Messages in this thread | | | Date | Wed, 21 Jan 2009 13:17:56 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH] workqueue: don't alloc_percpu for single workqueue |
| |
On 01/21, Lai Jiangshan wrote: > > allocating memory for every cpu for single workqueue is waste.
Yes, perhaps this makes sense, we can save a bit of per-cpu memory for each single-threaded wq, and the patch looks correct.
> -static struct cpu_workqueue_struct * > -init_cpu_workqueue(struct workqueue_struct *wq, int cpu) > +static void init_cpu_workqueue(struct workqueue_struct *wq, > + struct cpu_workqueue_struct *cwq) > { > - struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu); > - > cwq->wq = wq; > spin_lock_init(&cwq->lock); > INIT_LIST_HEAD(&cwq->worklist); > init_waitqueue_head(&cwq->more_work); > - > - return cwq; > }
Do we really need to change the prototype of init_cpu_workqueue() and change then change __create_workqueue_key() accordingly? Afaics, the only change in init_cpu_workqueue() we need is
- struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu); + struct cpu_workqueue_struct *cwq = wq_per_cpu(wq, cpu);
no?
> @@ -906,6 +907,13 @@ void destroy_workqueue(struct workqueue_struct *wq) > const struct cpumask *cpu_map = wq_cpu_map(wq); > int cpu; > > + if (is_wq_single_threaded(wq)) { > + cleanup_workqueue_thread(wq->cpu_wq); > + kfree(wq->cpu_wq); > + kfree(wq); > + return; > + }
again, not sure I understand why this change is needed. Afaics we only need to use kfree(wq->cpu_wq) instead of free_percpu() if it is single-threaded.
Oleg.
| |